wdiff rfc9559.original.xml rfc9559.xml

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<rfc version="3" ipr="trust200902" docName="draft-ietf-cellar-matroska-21" sortRefs="true" tocDepth="4" number="9559" submissionType="IETF" category="std"
consensus="true" tocInclude="true" sortRefs="true" symRefs="true" tocDepth="4" xml:lang="en" xmlns:xi="http://www.w3.org/2001/XInclude" indexInclude="true" consensus="true">
updates="8794" obsoletes="">

<front>
<title abbrev="Matroska Format">Matroska Media Container Format Specifications</title><seriesInfo value="draft-ietf-cellar-matroska-21" stream="IETF" status="standard" name="Internet-Draft"></seriesInfo> Specification</title>
<seriesInfo name="RFC" value="9559"/>

<author initials="S." surname="Lhomme" fullname="Steve Lhomme"><organization></organization><address><postal><street></street>
</postal><email>slhomme@matroska.org</email>
</address></author><author initials="M." surname="Bunkus" fullname="Moritz Bunkus"><organization></organization><address><postal><street></street>
</postal><email>moritz@bunkus.org</email>
</address></author><author initials="D." surname="Rice" fullname="Dave Rice"><organization></organization><address><postal><street></street>
</postal><email>dave@dericed.com</email>
</address></author><date year="2023" month="October" day="22"></date> year="2024" month="October"></date>
<area>art</area>
<workgroup>CELLAR Group</workgroup>
<workgroup>cellar</workgroup>
<keyword>binary</keyword>
<keyword>storage</keyword>
<keyword>matroska</keyword>
<keyword>ebml</keyword>
<keyword>webm</keyword>

<abstract>
<t>This document defines the Matroska audiovisual data container structure,
including definitions of its structural elements,
as well as its terminology,
vocabulary, and application.</t>
<t>This document updates <xref target="RFC8794"></xref> RFC 8794 to permit the use of a previously reserved EBML Extensible Binary Meta Language (EBML) Element ID.</t>
</abstract>

</front>

<middle>

<section anchor="introduction"><name>Introduction</name>
<t>Matroska is an audiovisual data container format. It was derived from a
project called <xref target="MCF"></xref>, target="MCF"/> but diverges from it
significantly because it is based on EBML (Extensible Binary Meta Language)
<xref target="RFC8794"></xref>, target="RFC8794"/>, a binary derivative of XML. EBML
provides significant advantages in terms of future format extensibility,
without breaking file support in parsers reading the previous versions.</t>
<t>First,
<t>To avoid any misunderstandings, it is essential to clarify exactly &quot;What
what an Audio/Video audio/video container is&quot;, to avoid any misunderstandings:</t>

<ul spacing="compact">
<li>It is:</t>

<ul>
<li><t>It is NOT a video or audio compression format (codec)</li>
<li>It (codec).</t>
</li>
<li><t>It is an envelope in which there can be many audio, video, and subtitles streams,
allowing the user to store a complete movie or CD in a single file.</li> file.</t>
</li>
</ul>
<t>Matroska is designed with the future in mind. It incorporates features such as:</t>

<ul spacing="compact">
<li>Fast

<ul>
<li><t>Fast seeking in the file</li>
<li>Chapter entries</li>
<li>Full file</t>
</li>
<li><t>Chapter entries</t>
</li>
<li><t>Full metadata (tags) support</li>
<li>Selectable support</t>
</li>
<li><t>Selectable subtitle/audio/video streams</li>
<li>Modularly expandable</li>
<li>Error streams</t>
</li>
<li><t>Modularly expandable</t>
</li>
<li><t>Error resilience (can recover playback even when the stream is damaged)</li>
<li>Streamable damaged)</t>
</li>
<li><t>Streamable over the internet Internet and local networks (HTTP <xref target="RFC9110"></xref>, target="RFC9110"/>, FTP <xref target="RFC0959"></xref>, target="RFC0959"/>, SMB <xref target="SMB-CIFS"></xref>, etc.)</li>
<li>Menus target="SMB-CIFS"/>, etc.)</t>
</li>
<li><t>Menus (like menus that DVDs have <xref target="DVD-Video"></xref>)</li> target="DVD-Video"/>)</t>
</li>
</ul>
</section>

<section anchor="status-of-this-document"><name>Status of this document</name> This Document</name>
<t>This document covers Matroska versions 1, 2, 3 3, and 4. Matroska v4 version 4 is the current version.
Matroska versions 1 to 3 are no longer maintained. No new elements are expected in files with version numbers 1, 2, or 3.</t>
</section>

<section anchor="notation-and-conventions"><name>Notation and Conventions</name>
<t>The key words &quot;<bcp14>MUST</bcp14>&quot;, &quot;<bcp14>MUST NOT</bcp14>&quot;,
&quot;<bcp14>REQUIRED</bcp14>&quot;, &quot;<bcp14>SHALL</bcp14>&quot;, &quot;<bcp14>SHALL NOT</bcp14>&quot;,
&quot;<bcp14>SHOULD</bcp14>&quot;, &quot;<bcp14>SHOULD NOT</bcp14>&quot;,
&quot;<bcp14>RECOMMENDED</bcp14>&quot;, &quot;<bcp14>NOT RECOMMENDED</bcp14>&quot;,
&quot;<bcp14>MAY</bcp14>&quot;, "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>",
"<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>",
"<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>",
"<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
"<bcp14>MAY</bcp14>", and &quot;<bcp14>OPTIONAL</bcp14>&quot; "<bcp14>OPTIONAL</bcp14>" in this document are
to be interpreted as described in BCP 14 <xref target="RFC2119"></xref> target="RFC2119"/>
<xref target="RFC8174"></xref> target="RFC8174"/> when, and only when, they appear in all capitals,
as shown here.</t>
<t>This document defines specific the following terms in order to
define the format and application of <tt>Matroska</tt>.
Specific terms are defined below:</t>

<dl spacing="compact">
<dt><tt>Matroska</tt>:</dt>
<dd>A Matroska:</t>

<dl>
<dt>Matroska:</dt>
<dd><t>A multimedia container format based on EBML (Extensible Binary Meta Language).</dd> Language).</t>
</dd>
<dt><tt>Matroska Reader</tt>:</dt>
<dd>A
<dd><t>A data parser that interprets the semantics of a Matroska document and creates a way for programs to use <tt>Matroska</tt>.</dd> Matroska.</t>
</dd>
<dt><tt>Matroska Player</tt>:</dt>
<dd>A
<dd><t>A <tt>Matroska Reader</tt> with a the primary purpose of playing audiovisual files, including <tt>Matroska</tt> documents.</dd> Matroska documents.</t>
</dd>
<dt><tt>Matroska Writer</tt>:</dt>
<dd>A
<dd><t>A data writer that creates <tt>Matroska</tt> documents.</dd> Matroska documents.</t>
</dd>
</dl>
</section>

<section anchor="matroska-overview"><name>Matroska Overview</name>

<section anchor="principles"><name>Principles</name>
<t>Matroska is a Document Type of EBML (Extensible Binary Meta Language). EBML.
This specification is dependent on the EBML Specification specification <xref target="RFC8794"></xref>. target="RFC8794"/>.
For an understanding of Matroska's EBML Schema, see in particular the sections of the EBML Specification covering specification that cover
EBML Element Types (Section 7), <xref target="RFC8794" sectionFormat="bare" section="7"/>),
EBML Schema (Section 11.1), <xref target="RFC8794" sectionFormat="bare" section="11.1"/>),
and EBML Structure (Section 3).</t> <xref target="RFC8794" sectionFormat="bare" section="3"/>).</t>
</section>

<section anchor="updates-to-rfc-8794"><name>Updates to RFC 8794</name>
<t>Because of an oversight, <xref target="RFC8794"></xref> target="RFC8794"/> reserved EBML ID 0x80, which is used by deployed Matroska implementations.
For this reason, this specification updates <xref target="RFC8794"></xref> target="RFC8794"/> to make 0x80 a legal EBML ID.
Specifically, Additionally, this specification makes the following are changed in <xref target="RFC8794"></xref>:</t> updates:</t>

<ul spacing="compact">
<li>From Errata 7189</li>
<li><xref target="RFC8794" sectionFormat="of" section="17.1"/> (per Erratum ID #7189 <xref target="Err7189"/>)</li>
</ul>
<t>In Section 17.1,</t>
<t>OLD:</t>
<t>One-octet
<blockquote><t>One-octet Element IDs MUST <bcp14>MUST</bcp14> be between 0x81 and
0xFE.  These items are valuable because they are short, and they need to be
used for commonly repeated elements.  Element IDs are to be allocated within
this range according to the &quot;RFC Required&quot; "RFC Required" policy [RFC8126].</t> <xref
target="RFC8126"/>.</t>
<t>The following one-octet Element IDs are RESERVED: 0xFF and 0x80.</t>
</blockquote>
<t>NEW:</t>
<t>One-octet
<blockquote><t>One-octet Element IDs MUST <bcp14>MUST</bcp14> be between 0x80 and
0xFE.  These items are valuable because they are short, and they need to be
used for commonly repeated elements.  Element IDs are to be allocated within
this range according to the &quot;RFC Required&quot; "RFC Required" policy [RFC8126].</t> <xref
target="RFC8126"/>.</t>
<t>The following one-octet Element ID is RESERVED: 0xFF.</t>
</blockquote>
<ul spacing="compact">
<li>From Errata 7191</li>
<li><xref target="RFC8794" sectionFormat="of" section="5"/> (per Erratum ID #7191 <xref target="Err7191"/>)</li>
</ul>
<t>In Section 5,</t>
<t>OLD:</t>

<artwork>
  +=========================+================+=================+
  | Element ID Octet Length | Range of Valid | Number of Valid |
  |                         |  Element IDs   |     Element IDs |
  +=========================+================+=================+
  |            1            |  0x81 - 0xFE   |             126 |
  +-------------------------+----------------+-----------------+

</artwork>
<t>NEW:</t>

<artwork>
  +=========================+================+=================+
  | Element ID Octet Length | Range of Valid | Number of Valid |
  |                         |  Element IDs   |     Element IDs |
  +=========================+================+=================+
  |            1            |  0x80 - 0xFE   |             127 |
  +-------------------------+----------------+-----------------+

</artwork>
</section>

<section anchor="added-ebml-constraints"><name>Added EBML Constraints</name>
<t>As an EBML Document Type, Matroska adds the following constraints to the EBML specification.</t>

<ul spacing="compact">
<li>The specification <xref target="RFC8794"/>:</t>

<ul>
<li><t>The <tt>docType</tt> of the <tt>EBML Header</tt> <bcp14>MUST</bcp14> be &quot;matroska&quot;.</li>
<li>The "matroska".</t>
</li>
<li><t>The <tt>EBMLMaxIDLength</tt> of the <tt>EBML Header</tt> <bcp14>MUST</bcp14> be 4.</li>
<li>The 4.</t>
</li>
<li><t>The <tt>EBMLMaxSizeLength</tt> of the <tt>EBML Header</tt> <bcp14>MUST</bcp14> be between 1 and 8 inclusive.</li> 8, inclusive.</t>
</li>
</ul>
</section>

<section anchor="design-rules"><name>Design Rules</name>
<t>The Root Element <tt>Root Element</tt> and all Top-Levels Elements <tt>Top-Level Elements</tt> <bcp14>MUST</bcp14> use 4 octets for their EBML Element ID -- i.e. Segment i.e., <tt>Segment</tt> and direct children of Segment.</t> <tt>Segment</tt>.</t>
<t>Legacy EBML/Matroska parsers did not handle Empty Elements properly, properly; elements were present in the file but with had a length of zero. 0.
They always assumed the value was 0 for integers/dates or 0x0p+0, the textual expression of floats using the format in <xref target="ISO9899"></xref> format, target="ISO9899"/>, no matter the default value of the element which that should have been used instead.
Therefore, Matroska writers <tt>Matroska Writers</tt> <bcp14>MUST NOT</bcp14> use EBML Empty Elements, Elements if the element has a default value that is not 0 for integers/dates and 0x0p+0 for floats.</t>
<t>When adding new elements to Matroska, these rules apply:</t>

<ul spacing="compact">
<li>A

<ul>
<li><t>A non-mandatory integer/date Element <bcp14>MUST NOT</bcp14> have a default value other than 0.</li>
<li>A 0.</t>
</li>
<li><t>A non-mandatory float Element <bcp14>MUST NOT</bcp14> have a default value other than 0x0p+0.</li>
<li>A 0x0p+0.</t>
</li>
<li><t>A non-mandatory string Element  <bcp14>MUST NOT</bcp14> have a default value, as empty string strings cannot be defined in the XML Schema.</li> Schema.</t>
</li>
</ul>
</section>

<section anchor="data-layout"><name>Data Layout</name>
<t>A Matroska file <bcp14>MUST</bcp14> be composed of at least one <tt>EBML Document</tt> using the <tt>Matroska Document Type</tt>.
Each <tt>EBML Document</tt> <bcp14>MUST</bcp14> start with an <tt>EBML Header</tt> and <bcp14>MUST</bcp14> be followed by the <tt>EBML Root Element</tt>, defined as <tt>Segment</tt> in Matroska. Matroska defines several <tt>Top-Level Elements</tt>
which
that may occur within the <tt>Segment</tt>.</t>
<t>As an example, a simple Matroska file consisting of a single <tt>EBML Document</tt> could be represented like this:</t>

<ul spacing="compact">
<li><tt>EBML Header</tt></li>
<li><tt>Segment</tt></li>
</ul>
<t>A more complex Matroska file consisting of an <tt>EBML Stream</tt> (consisting of two <tt>EBML Documents</tt>) could be represented like this:</t>

<ul spacing="compact">
<li><tt>EBML Header</tt></li>
<li><tt>Segment</tt></li>
<li><tt>EBML Header</tt></li>
<li><tt>Segment</tt></li>
</ul>
<t>The following diagram represents a simple Matroska file, comprised of an <tt>EBML Document</tt>
with an <tt>EBML Header</tt>, a <tt>Segment Element</tt> <tt>Segment</tt> element (the <tt>Root Element</tt>), and all eight Matroska
<tt>Top-Level Elements</tt>. In the following diagrams of in this section, horizontal spacing expresses
a parent-child relationship between Matroska Elements elements (e.g., the <tt>Info Element</tt> <tt>Info</tt> element is contained within
the <tt>Segment Element</tt>) <tt>Segment</tt> element), whereas vertical alignment represents the storage order within the file.</t>

<figure><name>Basic layout Layout of a Matroska file. File
</name>
<artwork>+-------------+
<artwork>
+-------------+
| EBML Header |
+---------------------------+
| Segment     | SeekHead    |
|             |-------------|
|             | Info        |
|             |-------------|
|             | Tracks      |
|             |-------------|
|             | Chapters    |
|             |-------------|
|             | Cluster     |
|             |-------------|
|             | Cues        |
|             |-------------|
|             | Attachments |
|             |-------------|
|             | Tags        |
+---------------------------+

</artwork>
</figure>
<t>The Matroska <tt>EBML Schema</tt> defines eight <tt>Top-Level Elements</tt>:</t>

<ul spacing="compact">
<li><tt>SeekHead</tt>

<ul>
<li><t><tt>SeekHead</tt> (<xref target="seekhead"></xref>),</li>
<li><tt>Info</tt> target="seekhead"/>)</t>
</li>
<li><t><tt>Info</tt> (<xref target="info"></xref>),</li>
<li><tt>Tracks</tt> target="info"/>)</t>
</li>
<li><t><tt>Tracks</tt> (<xref target="track-flags"></xref>),</li>
<li><tt>Chapters</tt> target="track-flags"/>)</t>
</li>
<li><t><tt>Chapters</tt> (<xref target="chapters"></xref>),</li>
<li><tt>Cluster</tt> target="chapters"/>)</t>
</li>
<li><t><tt>Cluster</tt> (<xref target="cluster-blocks"></xref>),</li>
<li><tt>Cues</tt> target="cluster-blocks"/>)</t>
</li>
<li><t><tt>Cues</tt> (<xref target="cues"></xref>),</li>
<li><tt>Attachments</tt> target="cues"/>)</t>
</li>
<li><t><tt>Attachments</tt> (<xref target="attachments-1"></xref>),</li>
<li>and <tt>Tags</tt> target="attachments-1"/>)</t>
</li>
<li><t><tt>Tags</tt> (<xref target="tags"></xref>).</li> target="tags"/>)</t>
</li>
</ul>
<t>The <tt>SeekHead Element</tt> <tt>SeekHead</tt> element (also known as <tt>MetaSeek</tt>) contains an
index of <tt>Top-Level Elements</tt> locations within the
<tt>Segment</tt>. Use of the <tt>SeekHead Element</tt> <tt>SeekHead</tt> element is
<bcp14>RECOMMENDED</bcp14>. Without a <tt>SeekHead Element</tt>, <tt>SeekHead</tt> element, a Matroska
parser would have to search the entire file to find all of the other
<tt>Top-Level Elements</tt>.  This is due to Matroska's flexible ordering
requirements; for instance, it is acceptable for the <tt>Chapters Element</tt> <tt>Chapters</tt> element
to be stored after the <tt>Cluster Elements</tt>.</t> <tt>Cluster</tt> element(s).</t>
<figure><name>Representation of a <tt>SeekHead Element</tt>. <tt>SeekHead</tt> Element
</name>
<artwork>+--------------------------------+
<artwork>
+--------------------------------+
| SeekHead | Seek | SeekID       |
|          |      |--------------|
|          |      | SeekPosition |
+--------------------------------+

</artwork>
</figure>
<t>The <tt>Info Element</tt> <tt>Info</tt> element contains vital information for identifying the whole <tt>Segment</tt>.
This includes the title for the <tt>Segment</tt>, a randomly generated unique identifier, identifier (UID),
and the unique identifier(s) UID(s) of any linked <tt>Segment Elements</tt>.</t> <tt>Segment</tt> elements.</t>
<figure><name>Representation of an <tt>Info Element</tt> <tt>Info</tt> Element and its Its <tt>Child Elements</tt>. Elements</tt>

</name>
<artwork>+-------------------------+
<artwork>
+-------------------------+
| Info | SegmentUUID      |
|      |------------------|
|      | SegmentFilename  |
|      |------------------|
|      | PrevUUID         |
|      |------------------|
|      | PrevFilename     |
|      |------------------|
|      | NextUUID         |
|      |------------------|
|      | NextFilename     |
|      |------------------|
|      | SegmentFamily    |
|      |------------------|
|      | ChapterTranslate |
|      |------------------|
|      | TimestampScale   |
|      |------------------|
|      | Duration         |
|      |------------------|
|      | DateUTC          |
|      |------------------|
|      | Title            |
|      |------------------|
|      | MuxingApp        |
|      |------------------|
|      | WritingApp       |
|-------------------------|

</artwork>
</figure>
<t>The <tt>Tracks Element</tt> <tt>Tracks</tt> element defines the technical details for each track and can store the name,
number, unique identifier, UID, language, and type (audio, video, subtitles, etc.) of each track.
For example, the <tt>Tracks Element</tt> <tt>Tracks</tt> element <bcp14>MAY</bcp14> store information about the resolution of a video track
or sample rate of an audio track.</t>
<t>The <tt>Tracks Element</tt> <tt>Tracks</tt> element <bcp14>MUST</bcp14> identify all the data needed by the codec to decode the data of the
specified track. However, the data required is contingent on the codec used for the track.
For example, a <tt>Track Element</tt> <tt>Track</tt> element for uncompressed audio only requires the audio bit rate to be present.
A codec such as AC-3 would require that the <tt>CodecID Element</tt> <tt>CodecID</tt> element be present for all tracks,
as it is the primary way to identify which codec to use to decode the track.</t>
<figure><name>Representation of the <tt>Tracks Element</tt> <tt>Tracks</tt> Element and a selection Selection of its <tt>Descendant Elements</tt>. Its <tt>Descendant</tt> Elements
</name>
<artwork>+------------------------------------+
<artwork>
+------------------------------------+
| Tracks | TrackEntry | TrackNumber  |
|        |            |--------------|
|        |            | TrackUID     |
|        |            |--------------|
|        |            | TrackType    |
|        |            |--------------|
|        |            | Name         |
|        |            |--------------|
|        |            | Language     |
|        |            |--------------|
|        |            | CodecID      |
|        |            |--------------|
|        |            | CodecPrivate |
|        |            |--------------|
|        |            | CodecName    |
|        |            |----------------------------------+
|        |            | Video        | FlagInterlaced    |
|        |            |              |-------------------|
|        |            |              | FieldOrder        |
|        |            |              |-------------------|
|        |            |              | StereoMode        |
|        |            |              |-------------------|
|        |            |              | AlphaMode         |
|        |            |              |-------------------|
|        |            |              | PixelWidth        |
|        |            |              |-------------------|
|        |            |              | PixelHeight       |
|        |            |              |-------------------|
|        |            |              | DisplayWidth      |
|        |            |              |-------------------|
|        |            |              | DisplayHeight     |
|        |            |              |-------------------|
|        |            |              | AspectRatioType   |
|        |            |              |-------------------|
|        |            |              | Color Colour            |
|        |            |----------------------------------|
|        |            | Audio        | SamplingFrequency |
|        |            |              |-------------------|
|        |            |              | Channels          |
|        |            |              |-------------------|
|        |            |              | BitDepth          |
|--------------------------------------------------------|

</artwork>
</figure>
<t>The <tt>Chapters Element</tt> <tt>Chapters</tt> element lists all of the chapters. Chapters <tt>Chapters</tt> are a way to set predefined
points to jump to in video or audio.</t>
<figure><name>Representation of the <tt>Chapters Element</tt> <tt>Chapters</tt> Element and a selection Selection of its <tt>Descendant Elements</tt>. Its <tt>Descendant</tt> Elements

</name>
<artwork>+-----------------------------------------+
<artwork>
+-----------------------------------------+
| Chapters | Edition | EditionUID         |
|          | Entry   |--------------------|
|          |         | EditionFlagDefault |
|          |         |--------------------|
|          |         | EditionFlagOrdered |
|          |         |---------------------------------+
|          |         | ChapterAtom | ChapterUID        |
|          |         |             |-------------------|
|          |         |             | ChapterStringUID  |
|          |         |             |-------------------|
|          |         |             | ChapterTimeStart  |
|          |         |             |-------------------|
|          |         |             | ChapterTimeEnd    |
|          |         |             |-------------------|
|          |         |             | ChapterFlagHidden |
|          |         |             |-------------------------------+
|          |         |             | ChapterDisplay | ChapString   |
|          |         |             |                |--------------|
|          |         |             |                | ChapLanguage |
+------------------------------------------------------------------+

</artwork>
</figure>
<t><tt>Cluster Elements</tt>
<t><tt>Cluster</tt> elements contain the content for each track, e.g., video frames. A Matroska file
<bcp14>SHOULD</bcp14> contain at least one <tt>Cluster Element</tt>. <tt>Cluster</tt> element.
In the rare case it doesn't, there should be a form of Segment linking with other Segments, method for <tt>Segments</tt> to link
together, possibly using Chapters, <tt>Chapters</tt>; see <xref target="linked-segments"></xref>.</t> target="linked-segments"/>.</t>
<t>The <tt>Cluster Element</tt> <tt>Cluster</tt> element helps to break up
<tt>SimpleBlock</tt> or <tt>BlockGroup Elements</tt> <tt>BlockGroup</tt> elements and helps with seeking and error protection.
Every <tt>Cluster Element</tt> <tt>Cluster</tt> element <bcp14>MUST</bcp14> contain a <tt>Timestamp Element</tt>. <tt>Timestamp</tt> element.
This <bcp14>SHOULD</bcp14> be the <tt>Timestamp Element</tt> <tt>Timestamp</tt> element used to play the first <tt>Block</tt> in the <tt>Cluster Element</tt>, <tt>Cluster</tt> element,
unless a different value is needed to accommodate for more Blocks, <tt>Blocks</tt>; see <xref target="block-timestamps"></xref>.</t>
<t><tt>Cluster Elements</tt> target="block-timestamps"/>.</t>
<t><tt>Cluster</tt> elements contain one or more block <tt>Block</tt> element, such as <tt>BlockGroup</tt> or <tt>SimpleBlock</tt> elements.
In some situations, a <tt>Cluster Element</tt> <tt>Cluster</tt> element <bcp14>MAY</bcp14> contain no block <tt>Block</tt> element, for example example, in a live recording
when no data has been collected.</t>
<t>A <tt>BlockGroup Element</tt> <tt>BlockGroup</tt> element <bcp14>MAY</bcp14> contain a <tt>Block</tt> of data and any information relating directly to that <tt>Block</tt>.</t>
<figure><name>Representation of a <tt>Cluster Element</tt> <tt>Cluster</tt> Element and its immediate Its Immediate <tt>Child Elements</tt>. Elements</tt>

</name>
<artwork>+--------------------------+
<artwork>
+--------------------------+
| Cluster | Timestamp      |
|         |----------------|
|         | Position       |
|         |----------------|
|         | PrevSize       |
|         |----------------|
|         | SimpleBlock    |
|         |----------------|
|         | BlockGroup     |
+--------------------------+

</artwork>
</figure>
<figure><name>Representation of the <tt>Block Element</tt> structure. <tt>Block</tt> Element Structure
</name>
<artwork>+----------------------------------+
<artwork>
+----------------------------------+
| Block | Portion of | Data Type   |
|       | a Block    |  - Bit Flag |
|       |--------------------------+
|       | Header     | TrackNumber |
|       |            |-------------|
|       |            | Timestamp   |
|       |            |-------------|
|       |            | Flags       |
|       |            |  - Gap      |
|       |            |  - Lacing   |
|       |            |  - Reserved |
|       |--------------------------|
|       | Optional   | FrameSize   |
|       |--------------------------|
|       | Data       | Frame       |
+----------------------------------+

</artwork>
</figure>
<t>Each <tt>Cluster</tt> <bcp14>MUST</bcp14> contain exactly one <tt>Timestamp Element</tt>. <tt>Timestamp</tt> element. The <tt>Timestamp Element</tt> <tt>Timestamp</tt> element value <bcp14>MUST</bcp14>
be stored once per <tt>Cluster</tt>. The <tt>Timestamp Element</tt> <tt>Timestamp</tt> element in the <tt>Cluster</tt> is relative to the entire <tt>Segment</tt>.
The <tt>Timestamp Element</tt> <tt>Timestamp</tt> element <bcp14>SHOULD</bcp14> be the first <tt>Element</tt> element in the <tt>Cluster</tt> it belongs to, to or the second <tt>Element</tt> element if that Cluster <tt>Cluster</tt> contains a CRC-32 <tt>CRC-32</tt> element (<xref target="crc-32"></xref>)</t> target="crc-32"/>).</t>
<t>Additionally, the <tt>Block</tt> contains an offset that, when added to the <tt>Cluster</tt>'s <tt>Timestamp Element</tt> <tt>Timestamp</tt> element value,
yields the <tt>Block</tt>'s effective timestamp. Therefore, the timestamp in the <tt>Block</tt> itself is relative to
the <tt>Timestamp Element</tt> <tt>Timestamp</tt> element in the <tt>Cluster</tt>. For example, if the <tt>Timestamp Element</tt> <tt>Timestamp</tt> element in the <tt>Cluster</tt>
is set to 10 seconds and a <tt>Block</tt> in that <tt>Cluster</tt> is supposed to be played 12 seconds into the clip,
the timestamp in the <tt>Block</tt> would be set to 2 seconds.</t>
<t>The <tt>ReferenceBlock</tt> in the <tt>BlockGroup</tt> is used instead of the basic &quot;P-frame&quot;/&quot;B-frame&quot; "P-frame"/"B-frame" description.
Instead of simply saying that this <tt>Block</tt> depends on the <tt>Block</tt> directly before, before or directly afterwards, after,
the <tt>Timestamp</tt> of the necessary <tt>Block</tt> is used. Because there can be as many <tt>ReferenceBlock Elements</tt> <tt>ReferenceBlock</tt> elements
as necessary for a <tt>Block</tt>, it allows for some extremely complex referencing.</t>
<t>The <tt>Cues Element</tt> <tt>Cues</tt> element is used to seek when playing back a file by providing a temporal index
for some of the <tt>Tracks</tt>. It is similar to the <tt>SeekHead Element</tt>, <tt>SeekHead</tt> element but is used for seeking to a specific time when playing back the file. It is possible to seek without this element,
but it is much more difficult because a <tt>Matroska Reader</tt> would have to 'hunt "hunt and peck' peck"
through the file looking to look for the correct timestamp.</t>
<t>The <tt>Cues Element</tt> <tt>Cues</tt> element <bcp14>SHOULD</bcp14> contain at least one <tt>CuePoint Element</tt>. <tt>CuePoint</tt> element. Each <tt>CuePoint Element</tt> <tt>CuePoint</tt> element
stores the position of the <tt>Cluster</tt> that contains the <tt>BlockGroup</tt> or <tt>SimpleBlock Element</tt>. <tt>SimpleBlock</tt> element.
The timestamp is stored in the <tt>CueTime Element</tt> <tt>CueTime</tt> element, and the location is stored in the <tt>CueTrackPositions Element</tt>.</t> <tt>CueTrackPositions</tt> element.</t>
<t>The <tt>Cues Element</tt> <tt>Cues</tt> element is flexible. For instance, <tt>Cues Element</tt> the <tt>Cues</tt> element can be used to index every
single timestamp of every <tt>Block</tt> or they can be indexed selectively.</t>
<figure><name>Representation of a <tt>Cues Element</tt> <tt>Cues</tt> Element and two levels Two Levels of its <tt>Descendant Elements</tt>. Its <tt>Descendant</tt> Elements
</name>
<artwork>+-------------------------------------+
<artwork>
+-------------------------------------+
| Cues | CuePoint | CueTime           |
|      |          |-------------------|
|      |          | CueTrackPositions |
|      |------------------------------|
|      | CuePoint | CueTime           |
|      |          |-------------------|
|      |          | CueTrackPositions |
+-------------------------------------+

</artwork>
</figure>
<t>The <tt>Attachments Element</tt> <tt>Attachments</tt> element is for attaching files to a Matroska file file, such as pictures,
fonts, webpages, web pages, etc.</t>
<figure><name>Representation of an <tt>Attachments Element</tt>. <tt>Attachments</tt> Element
</name>
<artwork>+------------------------------------------------+
<artwork>
+------------------------------------------------+
| Attachments | AttachedFile | FileDescription   |
|             |              |-------------------|
|             |              | FileName          |
|             |              |-------------------|
|             |              | FileMediaType     |
|             |              |-------------------|
|             |              | FileData          |
|             |              |-------------------|
|             |              | FileUID           |
|             |              |-------------------|
|             |              | FileName          |
|             |              |-------------------|
|             |              | FileReferral      |
|             |              |-------------------|
|             |              | FileUsedStartTime |
|             |              |-------------------|
|             |              | FileUsedEndTime   |
+------------------------------------------------+

</artwork>
</figure>
<t>The <tt>Tags Element</tt> <tt>Tags</tt> element contains metadata that describes the <tt>Segment</tt> and potentially
its <tt>Tracks</tt>, <tt>Chapters</tt>, and <tt>Attachments</tt>. Each <tt>Track</tt> or <tt>Chapter</tt> that those tags
applies to has its UID listed in the <tt>Tags</tt>. The <tt>Tags</tt> contain all extra information about
the file: scriptwriter, singer, scriptwriters, singers, actors, directors, titles, edition, price, dates, genre, comments,
etc. Tags <tt>Tags</tt> can contain their values in multiple languages.
For example, a movie's &quot;title&quot; <tt>Tag</tt> "TITLE" tag value might contain both the original
English title as well as the title it was released as in Germany.</t> German title.</t>
<figure><name>Representation of a <tt>Tags Element</tt> <tt>Tags</tt> Element and three levels Three Levels of its Its <tt>Children Elements</tt>. Elements</tt>
</name>
<artwork>+-------------------------------------------+
<artwork>
+-------------------------------------------+
| Tags | Tag | Targets   | TargetTypeValue  |
|      |     |           |------------------|
|      |     |           | TargetType       |
|      |     |           |------------------|
|      |     |           | TagTrackUID      |
|      |     |           |------------------|
|      |     |           | TagEditionUID    |
|      |     |           |------------------|
|      |     |           | TagChapterUID    |
|      |     |           |------------------|
|      |     |           | TagAttachmentUID |
|      |     |------------------------------|
|      |     | SimpleTag | TagName          |
|      |     |           |------------------|
|      |     |           | TagLanguage      |
|      |     |           |------------------|
|      |     |           | TagDefault       |
|      |     |           |------------------|
|      |     |           | TagString        |
|      |     |           |------------------|
|      |     |           | TagBinary        |
|      |     |           |------------------|
|      |     |           | SimpleTag        |
+-------------------------------------------+

</artwork>
</figure>
</section>
</section>

<section anchor="matroska-schema"><name>Matroska Schema</name>
<t>This specification includes an <tt>EBML Schema</tt>, which Schema</tt> that defines the Elements elements and structure
of Matroska using the EBML Schema elements and attributes defined in Section 11.1 of <xref target="RFC8794"></xref>.
The EBML Schema defines every valid Matroska element in a manner defined by the EBML specification.</t> target="RFC8794" sectionFormat="of" section="11.1"/>.</t>
<t>Attributes using their default value like (like <tt>minOccurs</tt>, <tt>minver</tt>, etc. etc.) or attributes with undefined values like (like <tt>length</tt>, <tt>maxver</tt>, etc. etc.) are omitted.</t>
<t>Here the definition of
<t>The definitions for each Matroska Element is provided.</t> element are provided below.</t>

<section anchor="segment-element"><name>Segment Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x18538067 / master</dd>
</dl>
<t>unknownsizeallowed: True</t>

<dl spacing="compact">
<dt>unknownsizeallowed:</dt>
<dd>True</dd>
<dt>path:</dt>
<dd><tt>\Segment</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The Root Element <tt>Root Element</tt> that contains all other Top-Level Elements; <tt>Top-Level Elements</tt>; see <xref target="data-layout"></xref>.</dd> target="data-layout"/>.</dd>
</dl>

<section anchor="seekhead-element"><name>SeekHead Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x114D9B74 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\SeekHead</tt></dd>
<dt>maxOccurs:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>Contains seeking information of Top-Level Elements; <tt>Top-Level Elements</tt>; see <xref target="data-layout"></xref>.</dd> target="data-layout"/>.</dd>
</dl>

<section anchor="seek-element"><name>Seek Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4DBB / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\SeekHead\Seek</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Contains a single seek entry to an EBML Element.</dd>
</dl>

<section anchor="seekid-element"><name>SeekID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x53AB / binary</dd>
<dt>length:</dt>
<dd>4</dd>
<dt>path:</dt>
<dd><tt>\Segment\SeekHead\Seek\SeekID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The binary EBML ID of a Top-Level Element.</dd> <tt>Top-Level Element</tt>.</dd>
</dl>
</section>

<section anchor="seekposition-element"><name>SeekPosition Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x53AC / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\SeekHead\Seek\SeekPosition</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The Segment Position <tt>Segment Position</tt> (<xref target="segment-position"></xref>) target="segment-position"/>) of a Top-Level Element.</dd> <tt>Top-Level Element</tt>.</dd>
</dl>
</section>
</section>
</section>

<section anchor="info-element"><name>Info Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x1549A966 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
</dl>
<t>recurring: True</t>

<dl spacing="compact">
<dt>recurring:</dt>
<dd>True</dd>
<dt>definition:</dt>
<dd>Contains general information about the Segment.</dd> <tt>Segment</tt>.</dd>
</dl>

<section anchor="segmentuuid-element"><name>SegmentUUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x73A4 / binary</dd>
<dt>length:</dt>
<dd>16</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\SegmentUUID</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A randomly generated unique ID to identify UID that identifies the Segment <tt>Segment</tt> amongst many others (128 bits). It is equivalent to a UUID Universally Unique Identifier (UUID) v4 <xref target="RFC4122"></xref> target="RFC9562"/> with all bits randomly (or pseudo-randomly) pseudorandomly) chosen.  An actual UUID v4 value, where some bits are not random, <bcp14>MAY</bcp14> also be used.</dd>
<dt>usage notes:</dt>
<dd>If the Segment <tt>Segment</tt> is a part of a Linked Segment, <tt>Linked Segment</tt>, then this Element element is <bcp14>REQUIRED</bcp14>.
The value of the unique ID UID <bcp14>MUST</bcp14> contain at least one bit set to 1.</dd>
</dl>
</section>

<section anchor="segmentfilename-element"><name>SegmentFilename Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x7384 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\SegmentFilename</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A filename corresponding to this Segment.</dd> <tt>Segment</tt>.</dd>
</dl>
</section>

<section anchor="prevuuid-element"><name>PrevUUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x3CB923 / binary</dd>
<dt>length:</dt>
<dd>16</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\PrevUUID</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>An ID to identify that identifies the previous Segment <tt>Segment</tt> of a Linked Segment.</dd> <tt>Linked Segment</tt>.</dd>
<dt>usage notes:</dt>
<dd>If the Segment <tt>Segment</tt> is a part of a Linked Segment <tt>Linked Segment</tt> that uses
Hard Linking (<xref target="hard-linking"></xref>), target="hard-linking"/>), then either the PrevUUID
<tt>PrevUUID</tt> or the NextUUID Element <tt>NextUUID</tt> element is
<bcp14>REQUIRED</bcp14>. If a Segment <tt>Segment</tt> contains a PrevUUID <tt>PrevUUID</tt>
but not a NextUUID, <tt>NextUUID</tt>, then it <bcp14>MAY</bcp14> be considered as the
last Segment <tt>Segment</tt> of the Linked Segment. <tt>Linked Segment</tt>. The PrevUUID <tt>PrevUUID</tt>
<bcp14>MUST NOT</bcp14> be equal to the SegmentUUID.</dd> <tt>SegmentUUID</tt>.</dd>
</dl>
</section>

<section anchor="prevfilename-element"><name>PrevFilename Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x3C83AB / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\PrevFilename</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A filename corresponding to the file of the previous Linked Segment.</dd> <tt>Linked Segment</tt>.</dd>
<dt>usage notes:</dt>
<dd>Provision of the previous filename is for display convenience,
but PrevUUID <tt>PrevUUID</tt> <bcp14>SHOULD</bcp14> be considered authoritative for identifying the previous Segment <tt>Segment</tt> in a Linked Segment.</dd> <tt>Linked Segment</tt>.</dd>
</dl>
</section>

<section anchor="nextuuid-element"><name>NextUUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x3EB923 / binary</dd>
<dt>length:</dt>
<dd>16</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\NextUUID</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>An ID to identify that identifies the next Segment <tt>Segment</tt> of a Linked Segment.</dd> <tt>Linked Segment</tt>.</dd>
<dt>usage notes:</dt>
<dd>If the Segment <tt>Segment</tt> is a part of a Linked Segment <tt>Linked Segment</tt> that uses Hard Linking (<xref target="hard-linking"></xref>), target="hard-linking"/>),
then either the PrevUUID <tt>PrevUUID</tt> or the NextUUID Element <tt>NextUUID</tt> element is <bcp14>REQUIRED</bcp14>. If a Segment <tt>Segment</tt> contains a NextUUID <tt>NextUUID</tt> but not a PrevUUID, <tt>PrevUUID</tt>, then it <bcp14>MAY</bcp14> be considered as the first Segment <tt>Segment</tt> of the Linked Segment. <tt>Linked Segment</tt>. The NextUUID <tt>NextUUID</tt> <bcp14>MUST NOT</bcp14> be equal to the SegmentUUID.</dd> <tt>SegmentUUID</tt>.</dd>
</dl>
</section>

<section anchor="nextfilename-element"><name>NextFilename Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x3E83BB / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\NextFilename</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A filename corresponding to the file of the next Linked Segment.</dd> <tt>Linked Segment</tt>.</dd>
<dt>usage notes:</dt>
<dd>Provision of the next filename is for display convenience,
but NextUUID <tt>NextUUID</tt> <bcp14>SHOULD</bcp14> be considered authoritative for identifying the Next Segment.</dd> <tt>Segment</tt>.</dd>
</dl>
</section>

<section anchor="segmentfamily-element"><name>SegmentFamily Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4444 / binary</dd>
<dt>length:</dt>
<dd>16</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\SegmentFamily</tt></dd>
<dt>definition:</dt>
<dd>A unique ID UID that all Segments <tt>Segments</tt> of a Linked Segment <tt>Linked Segment</tt> <bcp14>MUST</bcp14> share (128 bits). It is equivalent to a UUID v4 <xref target="RFC4122"></xref> target="RFC9562"/> with all bits randomly (or pseudo-randomly) pseudorandomly) chosen. An actual UUID v4 value, where some bits are not random, <bcp14>MAY</bcp14> also be used.</dd>
<dt>usage notes:</dt>
<dd>If the Segment Info <tt>Segment</tt> <tt>Info</tt> contains a <tt>ChapterTranslate</tt> element, this Element element is <bcp14>REQUIRED</bcp14>.</dd>
</dl>
</section>

<section anchor="chaptertranslate-element"><name>ChapterTranslate Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6924 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\ChapterTranslate</tt></dd>
<dt>definition:</dt>
<dd>The mapping between this <tt>Segment</tt> and a
segment value in the given Chapter Codec.</dd>
<dt>rationale:</dt>
<dd>Chapter Codec Codecs may need to address different segments, but they may not know of the way to identify such segment segments when stored in Matroska.
This element and its child elements add a way to map the internal segments known to the Chapter Codec to the Segment IDs <tt>SegmentUUID</tt>s in Matroska.
This allows remuxing a file with Chapter Codec without changing the content of the codec data, just the Segment <tt>Segment</tt> mapping.</dd>
</dl>

<section anchor="chaptertranslateid-element"><name>ChapterTranslateID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x69A5 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\ChapterTranslate\ChapterTranslateID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The binary value used to represent this Segment <tt>Segment</tt> in the chapter codec data.
The format depends on the ChapProcessCodecID <tt>ChapProcessCodecID</tt> used; see <xref target="chapprocesscodecid-element"></xref>.</dd> target="chapprocesscodecid-element"/>.</dd>
</dl>
</section>

<section anchor="chaptertranslatecodec-element"><name>ChapterTranslateCodec Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x69BF / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\ChapterTranslate\ChapterTranslateCodec</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>This <tt>ChapterTranslate</tt> applies
<dd>Applies to this the chapter codec of the given chapter edition(s); see <xref target="chapprocesscodecid-element"></xref>.</dd>
</dl>
<t>defined values:</t>
<table anchor="ChapterTranslateCodecValues"><name>ChapterTranslateCodec values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">Matroska Script</td>
<td align="left">Chapter commands using the Matroska Script codec.</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">DVD-menu</td>
<td align="left">Chapter commands using target="chapprocesscodecid-element"/>.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ChapProcessCodecIDValues"/>. Additional values can be registered in the DVD-like codec.</td>
</tr>
</tbody>
</table></section> "Matroska Chapter Codec
   IDs" registry defined in <xref target="matroska-chapter-codec-ids-registry"/>.</dd>
</dl>
</section>

<section anchor="chaptertranslateeditionuid-element"><name>ChapterTranslateEditionUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x69FC / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\ChapterTranslate\ChapterTranslateEditionUID</tt></dd>
<dt>definition:</dt>
<dd>Specify
<dd>Specifies a chapter edition UID on to which this <tt>ChapterTranslate</tt> applies.</dd>
<dt>usage notes:</dt>
<dd>When no <tt>ChapterTranslateEditionUID</tt> is specified in the <tt>ChapterTranslate</tt>, the <tt>ChapterTranslate</tt> applies to all chapter editions found in the Segment <tt>Segment</tt> using the given <tt>ChapterTranslateCodec</tt>.</dd>
</dl>
</section>
</section>

<section anchor="timestampscale-element"><name>TimestampScale Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x2AD7B1 / uinteger / 1000000</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\TimestampScale</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Base unit for Segment Ticks and Track Ticks, in nanoseconds. A TimestampScale <tt>TimestampScale</tt> value of 1000000 means scaled timestamps in the Segment <tt>Segment</tt> are expressed in milliseconds; see <xref target="timestamps"></xref> target="timestamps"/> on how to interpret timestamps.</dd>
</dl>
</section>

<section anchor="duration-element"><name>Duration Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4489 / float</dd>
<dt>range:</dt>
<dd>&gt; 0x0p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\Duration</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Duration of the Segment, <tt>Segment</tt>, expressed in Segment Ticks <tt>Segment</tt> Ticks, which is are based on TimestampScale; <tt>TimestampScale</tt>; see <xref target="timestamp-ticks"></xref>.</dd> target="timestamp-ticks"/>.</dd>
</dl>
</section>

<section anchor="dateutc-element"><name>DateUTC Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4461 / date</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\DateUTC</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>The date and time that the Segment <tt>Segment</tt> was created by the muxing application or library.</dd>
</dl>
</section>

<section anchor="title-element"><name>Title Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x7BA9 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\Title</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>General name of the Segment.</dd> <tt>Segment</tt>.</dd>
</dl>
</section>

<section anchor="muxingapp-element"><name>MuxingApp Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4D80 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\MuxingApp</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Muxing application or library (example: &quot;libmatroska-0.4.3&quot;).</dd> "libmatroska-0.4.3").</dd>
<dt>usage notes:</dt>
<dd>Include the full name of the application or library followed by the version number.</dd>
</dl>
</section>

<section anchor="writingapp-element"><name>WritingApp Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x5741 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Info\WritingApp</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Writing application (example: &quot;mkvmerge-0.3.3&quot;).</dd> "mkvmerge-0.3.3").</dd>
<dt>usage notes:</dt>
<dd>Include the full name of the application followed by the version number.</dd>
</dl>
</section>
</section>

<section anchor="cluster-element"><name>Cluster Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x1F43B675 / master</dd>
</dl>
<t>unknownsizeallowed: True</t>

<dl spacing="compact">
<dt>unknownsizeallowed:</dt>
<dd>True</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster</tt></dd>
<dt>definition:</dt>
<dd>The Top-Level Element <tt>Top-Level Element</tt> containing the (monolithic) Block <tt>Block</tt> structure.</dd>
</dl>

<section anchor="timestamp-element"><name>Timestamp Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE7 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\Timestamp</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Absolute timestamp of the cluster, expressed in Segment Ticks Ticks, which is are based on TimestampScale; <tt>TimestampScale</tt>; see <xref target="timestamp-ticks"></xref>.</dd> target="timestamp-ticks"/>.</dd>
<dt>usage notes:</dt>
<dd>This element <bcp14>SHOULD</bcp14> be the first child element of the Cluster <tt>Cluster</tt> it belongs to, to
or the second if that Cluster <tt>Cluster</tt> contains a CRC-32 <tt>CRC-32</tt> element (<xref target="crc-32"></xref>).</dd> target="crc-32"/>).</dd>
</dl>
</section>

<section anchor="position-element"><name>Position Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xA7 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\Position</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>maxver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The Segment Position <tt>Segment Position</tt> of the Cluster <tt>Cluster</tt> in the Segment <tt>Segment</tt> (0 in live streams).
It might help to resynchronise resynchronize the offset on damaged streams.</dd>
</dl>
</section>

<section anchor="prevsize-element"><name>PrevSize Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xAB / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\PrevSize</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Size of the previous Cluster, <tt>Cluster</tt>, in octets. Can be useful for backward playing.</dd>
</dl>
</section>

<section anchor="simpleblock-element"><name>SimpleBlock Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xA3 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\SimpleBlock</tt></dd>
<dt>minver:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>Similar to Block, see <tt>Block</tt> (see <xref target="block-structure"></xref>, target="block-structure"/>) but without all the extra information,
mostly information.
Mostly used to reduced reduce overhead when no extra feature is needed; see <xref target="simpleblock-structure"></xref> target="simpleblock-structure"/> on SimpleBlock <tt>SimpleBlock</tt> Structure.</dd>
</dl>
</section>

<section anchor="blockgroup-element"><name>BlockGroup Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xA0 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup</tt></dd>
<dt>definition:</dt>
<dd>Basic container of information containing a single Block <tt>Block</tt> and information specific to that Block.</dd> <tt>Block</tt>.</dd>
</dl>

<section anchor="block-element"><name>Block Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xA1 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\Block</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Block
<dd><tt>Block</tt> containing the actual data to be rendered and a timestamp relative to the Cluster <tt>Cluster</tt> Timestamp;
see <xref target="block-structure"></xref> target="block-structure"/> on Block <tt>Block</tt> Structure.</dd>
</dl>
</section>

<section anchor="blockadditions-element"><name>BlockAdditions Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x75A1 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\BlockAdditions</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Contain
<dd>Contains additional binary data to complete the main one; <tt>Block</tt> element; see Codec BlockAdditions section of <xref target="MatroskaCodec"></xref> target="I-D.ietf-cellar-codec" sectionFormat="of" section="4.1.5"/> for more information.
An EBML parser that has no knowledge of the Block <tt>Block</tt> structure could still see and use/skip these data.</dd>
</dl>

<section anchor="blockmore-element"><name>BlockMore Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xA6 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Contain
<dd>Contains the BlockAdditional <tt>BlockAdditional</tt> and some parameters.</dd>
</dl>
</section>

<section anchor="blockadditional-element"><name>BlockAdditional Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xA5 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\BlockAdditional</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Interpreted by the codec as it wishes (using the BlockAddID).</dd> <tt>BlockAddID</tt>).</dd>
</dl>
</section>

<section anchor="blockaddid-element"><name>BlockAddID Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0xEE / uinteger / 1</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\BlockAddID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>An ID to identify that identifies how to interpret the BlockAdditional <tt>BlockAdditional</tt> data; see Codec BlockAdditions section of <xref target="MatroskaCodec"></xref> target="I-D.ietf-cellar-codec" sectionFormat="of" section="4.1.5"/> for
more information. A value of 1 indicates that the meaning of the BlockAdditional <tt>BlockAdditional</tt> data is
defined by the codec. Any other value indicates that the meaning of the BlockAdditional <tt>BlockAdditional</tt> data is found in
should be handled according to the BlockAddIDType found <tt>BlockAddIDType</tt> that is located in the TrackEntry.</dd>
<tt>TrackEntry</tt>.</dd>
<dt>usage notes:</dt>
<dd>Each BlockAddID <tt>BlockAddID</tt> value <bcp14>MUST</bcp14> be unique between all BlockMore <tt>BlockMore</tt> elements found in a BlockAdditions.</dd>
<dt>usage notes:</dt>
<dd>To <tt>BlockAdditions</tt> element. To keep MaxBlockAdditionID <tt>MaxBlockAdditionID</tt> as low as possible, small values <bcp14>SHOULD</bcp14> be used.</dd>
</dl>
</section>
</section>

<section anchor="blockduration-element"><name>BlockDuration Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x9B / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\BlockDuration</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>see implementation notes
<dd>See <xref target="BlockDurationNotes"/> / 1</dd>
<dt>definition:</dt>
<dd>The duration of the Block, <tt>Block</tt>, expressed in Track Ticks; see <xref target="timestamp-ticks"></xref>.
target="timestamp-ticks"/>.  The BlockDuration Element <tt>BlockDuration</tt> element can be useful
at the end of a Track <tt>Track</tt> to define the duration of the last frame (as
there is no subsequent Block available), <tt>Block</tt> available) or when there is a break in a
track like for subtitle tracks.</dd>
<dt>notes:</dt>
<dd>See <xref target="BlockDurationNotes"/>.</dd>
</dl>
<t>notes:</t>
<table anchor="BlockDurationNotes"><name>BlockDuration implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">minOccurs</td>
<td align="left">BlockDuration align="left"><tt>BlockDuration</tt> <bcp14>MUST</bcp14> be set (minOccurs=1) if the associated TrackEntry <tt>TrackEntry</tt> stores a DefaultDuration <tt>DefaultDuration</tt> value.</td>
</tr>

<tr>
<td align="left">default</td>
<td align="left">When align="left">If a value is not written present and with no DefaultDuration, <tt>DefaultDuration</tt> is defined, the value is assumed to be the difference between the timestamp of this Block <tt>Block</tt> and the timestamp of the next Block <tt>Block</tt> in &quot;display&quot; "display" order (not coding order).</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="referencepriority-element"><name>ReferencePriority Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0xFA / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\ReferencePriority</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>This frame is referenced and has the specified cache priority.
In cache the cache, only a frame of the same or higher priority can replace this frame. A value of 0 means the frame is not referenced.</dd>
</dl>
</section>

<section anchor="referenceblock-element"><name>ReferenceBlock Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xFB / integer</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\ReferenceBlock</tt></dd>
<dt>definition:</dt>
<dd>A timestamp value, relative to the timestamp of the Block <tt>Block</tt> in this BlockGroup, <tt>BlockGroup</tt>, expressed in Track Ticks; see <xref target="timestamp-ticks"></xref>. target="timestamp-ticks"/>.
This is used to reference other frames necessary to decode this frame.
The relative value <bcp14>SHOULD</bcp14> correspond to a valid <tt>Block</tt> that this <tt>Block</tt> depends on.
Historically Matroska Writer
Historically, <tt>Matroska Writers</tt> didn't write the actual <tt>Block(s)</tt> that this <tt>Block</tt> depends on, but they did write <em>some</em> <tt>Block</tt> <tt>Block(s)</tt> in the past.</dd>
</dl>
<t>The value &quot;0&quot; "0" <bcp14>MAY</bcp14> also be used to signify that this <tt>Block</tt> cannot be decoded on its own, but without knownledge of which <tt>Block</tt> the necessary reference <tt>Block(s)</tt> is necessary. unknown. In this case, other <tt>ReferenceBlock</tt> elements <bcp14>MUST NOT</bcp14> be found in the same <tt>BlockGroup</tt>.</t>
<t>If <tt>BlockGroup</tt>. If the <tt>BlockGroup</tt> doesn't have any a <tt>ReferenceBlock</tt> element, then the <tt>Block</tt> it contains can be decoded without using any other <tt>Block</tt> data.</t>
</section>

<section anchor="codecstate-element"><name>CodecState Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xA4 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\CodecState</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>The new codec state to use. Data interpretation is private to the codec.
This information <bcp14>SHOULD</bcp14> always be referenced by a seek entry.</dd>
</dl>
</section>

<section anchor="discardpadding-element"><name>DiscardPadding Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x75A2 / integer</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\DiscardPadding</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Duration of the silent data added to the Block, <tt>Block</tt>, expressed in
Matroska Ticks -- i.e., in nanoseconds; see <xref target="timestamp-ticks"></xref> target="timestamp-ticks"/>
(padding at the end of the Block <tt>Block</tt> for positive value, values and at the
beginning of the Block <tt>Block</tt> for negative value). values).  The duration of DiscardPadding
<tt>DiscardPadding</tt> is not calculated in the duration of the TrackEntry
<tt>TrackEntry</tt> and <bcp14>SHOULD</bcp14> be discarded during
playback.</dd>
</dl>
</section>
</section>
</section>

<section anchor="tracks-element"><name>Tracks Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x1654AE6B / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
</dl>
<t>recurring: True</t>

<dl spacing="compact">
<dt>recurring:</dt>
<dd>True</dd>
<dt>definition:</dt>
<dd>A Top-Level Element <tt>Top-Level Element</tt> of information with many tracks described.</dd>
</dl>

<section anchor="trackentry-element"><name>TrackEntry Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xAE / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Describes a track with all Elements.</dd> elements.</dd>
</dl>

<section anchor="tracknumber-element"><name>TrackNumber Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xD7 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackNumber</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The track number as used in the Block <tt>Block</tt> Header.</dd>
</dl>
</section>

<section anchor="trackuid-element"><name>TrackUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x73C5 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackUID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>A unique ID to identify UID that identifies the Track.</dd>
</dl>
<t>stream copy: True <tt>Track</tt>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="tracktype-element"><name>TrackType Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x83 / uinteger</dd>
<dt>range:</dt>
<dd>not 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackType</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The <tt>TrackType</tt> defines the type of each frame found in the Track. <tt>Track</tt>.
The value <bcp14>SHOULD</bcp14> be stored on 1 octet.</dd>
<dt>defined values:</dt>
<dd>See <xref target="TrackTypeValues"/>. Additional values can be registered in the "Matroska Track Types" registry defined in <xref target="matroska-track-types-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>defined values:</t>
<table anchor="TrackTypeValues"><name>TrackType values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">each frame contains</th> align="left">contents of each frame</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>1</tt></td>
<td align="left">video</td>
<td align="left">An image.</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">audio</td>
<td align="left">Audio samples.</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">complex</td>
<td align="left">A mix of different other TrackType. <tt>TrackType</tt>. The codec needs to define how the <tt>Matroska Player</tt> should interpret such data.</td>
</tr>

<tr>
<td align="left"><tt>16</tt></td>
<td align="left">logo</td>
<td align="left">An image to be rendered over the video track(s).</td>
</tr>

<tr>
<td align="left"><tt>17</tt></td>
<td align="left">subtitle</td>
<td align="left">Subtitle or closed caption data to be rendered over the video track(s).</td>
</tr>

<tr>
<td align="left"><tt>18</tt></td>
<td align="left">buttons</td>
<td align="left">Interactive button(s) to be rendered over the video track(s).</td>
</tr>

<tr>
<td align="left"><tt>32</tt></td>
<td align="left">control</td>
<td align="left">Metadata used to control the player of the <tt>Matroska Player</tt>.</td>
</tr>

<tr>
<td align="left"><tt>33</tt></td>
<td align="left">metadata</td>
<td align="left">Timed metadata that can be passed on to the <tt>Matroska Player</tt>.</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="flagenabled-element"><name>FlagEnabled Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0xB9 / uinteger / 1</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagEnabled</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>Set to 1 if the track is usable. It is possible to turn a track that is not usable track into a usable track using chapter codecs or control tracks.</dd>
</dl>
</section>

<section anchor="flagdefault-element"><name>FlagDefault Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x88 / uinteger / 1</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagDefault</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Set to 1 if that the track (audio, video video, or subs) subtitles) is eligible for automatic selection by the player; see <xref target="default-track-selection"></xref> target="default-track-selection"/> for more details.</dd>
</dl>
</section>

<section anchor="flagforced-element"><name>FlagForced Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55AA / uinteger / 0</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagForced</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Applies only to subtitles. Set to 1 if that the track is eligible for automatic selection by the player if it matches the user's language preference,
even if the user's preferences would normally not normally enable subtitles with the selected audio track;
this can be used for tracks containing only translations of foreign-language audio in foreign languages or onscreen on-screen text.
See <xref target="default-track-selection"></xref> target="default-track-selection"/> for more details.</dd>
</dl>
</section>

<section anchor="flaghearingimpaired-element"><name>FlagHearingImpaired Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55AB / uinteger</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagHearingImpaired</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Set to 1 if and only if that the track is suitable for users with hearing impairments.</dd>
</dl>
</section>

<section anchor="flagvisualimpaired-element"><name>FlagVisualImpaired Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55AC / uinteger</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagVisualImpaired</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Set to 1 if and only if that the track is suitable for users with visual impairments.</dd>
</dl>
</section>

<section anchor="flagtextdescriptions-element"><name>FlagTextDescriptions Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55AD / uinteger</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagTextDescriptions</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Set to 1 if and only if that the track contains textual descriptions of video content.</dd>
</dl>
</section>

<section anchor="flagoriginal-element"><name>FlagOriginal Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55AE / uinteger</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagOriginal</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Set to 1 if and only if that the track is in the content's original language.</dd>
</dl>
</section>

<section anchor="flagcommentary-element"><name>FlagCommentary Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55AF / uinteger</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagCommentary</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Set to 1 if and only if that the track contains commentary.</dd>
</dl>
</section>

<section anchor="flaglacing-element"><name>FlagLacing Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x9C / uinteger / 1</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\FlagLacing</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Set to 1 if the track <bcp14>MAY</bcp14> contain blocks using that use lacing.
When set to 0 0, all blocks <bcp14>MUST</bcp14> have their lacing flags set to No lacing; "no lacing"; see <xref target="block-lacing"></xref> target="block-lacing"/> on Block 'Block' Lacing.</dd>
</dl>
</section>

<section anchor="defaultduration-element"><name>DefaultDuration Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x23E383 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\DefaultDuration</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Number of nanoseconds per frame, expressed in Matroska Ticks -- i.e., in nanoseconds; see <xref target="timestamp-ticks"></xref>
(frame target="timestamp-ticks"/>
("frame" in the Matroska sense -- one Element element put into a (Simple)Block).</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="defaultdecodedfieldduration-element"><name>DefaultDecodedFieldDuration Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x234E7A / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\DefaultDecodedFieldDuration</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The period between two successive fields at the output of the decoding process, expressed in Matroska Ticks -- i.e., in nanoseconds; see <xref target="timestamp-ticks"></xref>.
see target="timestamp-ticks"/>.
See <xref target="defaultdecodedfieldduration"></xref> target="defaultdecodedfieldduration"/> for more information</dd>
</dl>
<t>stream copy: True information.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="tracktimestampscale-element"><name>TrackTimestampScale Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x23314F / float / 0x1p+0</dd>
<dt>range:</dt>
<dd>&gt; 0x0p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackTimestampScale</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>maxver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>The scale to apply on this track to work at normal speed in relation with other tracks
(mostly used to adjust video speed when the audio length differs).</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="maxblockadditionid-element"><name>MaxBlockAdditionID Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55EE / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\MaxBlockAdditionID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The maximum value of BlockAddID <tt>BlockAddID</tt> (<xref target="blockaddid-element"></xref>). target="blockaddid-element"/>).
A value of 0 means there is no BlockAdditions <tt>BlockAdditions</tt> (<xref target="blockadditions-element"></xref>) target="blockadditions-element"/>) for this track.</dd>
</dl>
</section>

<section anchor="blockadditionmapping-element"><name>BlockAdditionMapping Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x41E4 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\BlockAdditionMapping</tt></dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Contains elements that extend the track format, format by adding content either to each frame,
with BlockAddID <tt>BlockAddID</tt> (<xref target="blockaddid-element"></xref>), target="blockaddid-element"/>), or to the track as a whole
with BlockAddIDExtraData.</dd> <tt>BlockAddIDExtraData</tt>.</dd>
</dl>

<section anchor="blockaddidvalue-element"><name>BlockAddIDValue Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x41F0 / uinteger</dd>
<dt>range:</dt>
<dd>&gt;=2</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDValue</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>If the track format extension needs content beside frames,
the value refers to the BlockAddID <tt>BlockAddID</tt> (<xref target="blockaddid-element"></xref>), target="blockaddid-element"/>) value being described.</dd>
<dt>usage notes:</dt>
<dd>To keep MaxBlockAdditionID <tt>MaxBlockAdditionID</tt> as low as possible, small values <bcp14>SHOULD</bcp14> be used.</dd>
</dl>
</section>

<section anchor="blockaddidname-element"><name>BlockAddIDName Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x41A4 / string</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDName</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>A human-friendly name describing the type of BlockAdditional <tt>BlockAdditional</tt> data,
as defined by the associated Block <tt>Block Additional Mapping.</dd> Mapping</tt>.</dd>
</dl>
</section>

<section anchor="blockaddidtype-element"><name>BlockAddIDType Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x41E7 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDType</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Stores the registered identifier of the Block <tt>Block Additional Mapping Mapping</tt>
to define how the BlockAdditional <tt>BlockAdditional</tt> data should be handled.</dd>
<dt>usage notes:</dt>
<dd>If BlockAddIDType <tt>BlockAddIDType</tt> is 0, the BlockAddIDValue <tt>BlockAddIDValue</tt> and corresponding BlockAddID <tt>BlockAddID</tt> values <bcp14>MUST</bcp14> be 1.</dd>
</dl>
</section>

<section anchor="blockaddidextradata-element"><name>BlockAddIDExtraData Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x41ED / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDExtraData</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Extra binary data that the BlockAddIDType <tt>BlockAddIDType</tt> can use to interpret the BlockAdditional <tt>BlockAdditional</tt> data.
The interpretation of the binary data depends on the BlockAddIDType <tt>BlockAddIDType</tt> value and the corresponding Block <tt>Block Additional Mapping.</dd> Mapping</tt>.</dd>
</dl>
</section>
</section>

<section anchor="name-element"><name>Name Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x536E / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Name</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A human-readable track name.</dd>
</dl>
</section>

<section anchor="language-element"><name>Language Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x22B59C / string / eng</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Language</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The language of the track,
in the Matroska languages form; see <xref target="language-codes"></xref> target="language-codes"/> on language codes.
This Element element <bcp14>MUST</bcp14> be ignored if the LanguageBCP47 Element <tt>LanguageBCP47</tt> element is used in the same TrackEntry.</dd> <tt>TrackEntry</tt>.</dd>
</dl>
</section>

<section anchor="languagebcp47-element"><name>LanguageBCP47 Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x22B59D / string</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\LanguageBCP47</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The language of the track,
in the form defined in <xref target="BCP47"></xref> form; target="RFC5646"/>; see <xref target="language-codes"></xref> target="language-codes"/> on language codes.
If this Element element is used, then any Language Elements <tt>Language</tt> elements used in the same TrackEntry <tt>TrackEntry</tt> <bcp14>MUST</bcp14> be ignored.</dd>
</dl>
</section>

<section anchor="codecid-element"><name>CodecID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x86 / string</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\CodecID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>An ID corresponding to the codec, codec;
see <xref target="MatroskaCodec"></xref> target="I-D.ietf-cellar-codec"/> for more info.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="codecprivate-element"><name>CodecPrivate Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x63A2 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\CodecPrivate</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Private data only known to the codec.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="codecname-element"><name>CodecName Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x258688 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\CodecName</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A human-readable string specifying the codec.</dd>
</dl>
</section>

<section anchor="attachmentlink-element"><name>AttachmentLink Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x7446 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\AttachmentLink</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>maxver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>The UID of an attachment that is used by this codec.</dd>
<dt>usage notes:</dt>
<dd>The value <bcp14>MUST</bcp14> match the <tt>FileUID</tt> value of an attachment found in this Segment.</dd> <tt>Segment</tt>.</dd>
</dl>
</section>

<section anchor="codecdelay-element"><name>CodecDelay Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x56AA / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\CodecDelay</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>CodecDelay is The codec-built-in delay,
<dd>The built-in delay for the codec, expressed in Matroska Ticks -- i.e., in nanoseconds; see <xref target="timestamp-ticks"></xref>. target="timestamp-ticks"/>.
It represents the amount number of codec samples that will be discarded by the decoder during playback.
This timestamp value <bcp14>MUST</bcp14> be subtracted from each frame timestamp in order to get the timestamp that will be actually played.
The value <bcp14>SHOULD</bcp14> be small so the muxing of tracks with the same actual timestamp are in the same Cluster.</dd>
</dl>
<t>stream copy: True <tt>Cluster</tt>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="seekpreroll-element"><name>SeekPreRoll Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x56BB / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\SeekPreRoll</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>After a discontinuity, SeekPreRoll is the duration of the data
that the decoder <bcp14>MUST</bcp14> decode before the decoded data is valid, expressed in Matroska Ticks -- i.e., in nanoseconds; see <xref target="timestamp-ticks"></xref>.</dd>
</dl>
<t>stream copy: True target="timestamp-ticks"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="tracktranslate-element"><name>TrackTranslate Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6624 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackTranslate</tt></dd>
<dt>definition:</dt>
<dd>The mapping between this <tt>TrackEntry</tt> and a track value in the given Chapter Codec.</dd>
<dt>rationale:</dt>
<dd>Chapter Codec Codecs may need to address content in a specific track, but they may not know of the way to identify tracks in Matroska.
This element and its child elements add a way to map the internal tracks known to the Chapter Codec to the track IDs in Matroska.
This allows remuxing a file with Chapter Codec without changing the content of the codec data, just the track mapping.</dd>
</dl>

<section anchor="tracktranslatetrackid-element"><name>TrackTranslateTrackID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x66A5 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateTrackID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The binary value used to represent this <tt>TrackEntry</tt> in the chapter codec data.
The format depends on the <tt>ChapProcessCodecID</tt> used; see <xref target="chapprocesscodecid-element"></xref>.</dd> target="chapprocesscodecid-element"/>.</dd>
</dl>
</section>

<section anchor="tracktranslatecodec-element"><name>TrackTranslateCodec Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x66BF / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateCodec</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>This <tt>TrackTranslate</tt> applies
<dd>Applies to this the chapter codec of the given chapter edition(s); see <xref target="chapprocesscodecid-element"></xref>.</dd>
</dl>
<t>defined values:</t>
<table anchor="TrackTranslateCodecValues"><name>TrackTranslateCodec values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">Matroska Script</td>
<td align="left">Chapter commands using the Matroska Script codec.</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">DVD-menu</td>
<td align="left">Chapter commands using target="chapprocesscodecid-element"/>.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ChapProcessCodecIDValues"/>. Additional values can be registered in the DVD-like codec.</td>
</tr>
</tbody>
</table></section> "Matroska Chapter Codec IDs" registry defined in <xref target="matroska-chapter-codec-ids-registry"/>.</dd>
</dl>
</section>

<section anchor="tracktranslateeditionuid-element"><name>TrackTranslateEditionUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x66FC / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateEditionUID</tt></dd>
<dt>definition:</dt>
<dd>Specify
<dd>Specifies a chapter edition UID on to which this <tt>TrackTranslate</tt> applies.</dd>
<dt>usage notes:</dt>
<dd>When no <tt>TrackTranslateEditionUID</tt> is specified in the <tt>TrackTranslate</tt>, the <tt>TrackTranslate</tt> applies to all chapter editions found in the Segment <tt>Segment</tt> using the given <tt>TrackTranslateCodec</tt>.</dd>
</dl>
</section>
</section>

<section anchor="video-element"><name>Video Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE0 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Video settings.</dd>
</dl>

<section anchor="flaginterlaced-element"><name>FlagInterlaced Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x9A / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\FlagInterlaced</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>Specify
<dd>Specifies whether the video frames in this track are interlaced.</dd>
<dt>restrictions:</dt>
<dd>See <xref target="FlagInterlacedValues"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>defined values:</t>
<table anchor="FlagInterlacedValues"><name>FlagInterlaced values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">undetermined</td>
<td align="left">Unknown status.This status. This value <bcp14>SHOULD</bcp14> be avoided.</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">interlaced</td>
<td align="left">Interlaced frames.</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">progressive</td>
<td align="left">No interlacing.</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="fieldorder-element"><name>FieldOrder Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x9D / uinteger / 2</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\FieldOrder</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Specify
<dd>Specifies the field ordering of video frames in this track.</dd>
<dt>restrictions:</dt>
<dd>See <xref target="FieldOrderValues"/>.</dd>
<dt>usage notes:</dt>
<dd>If <tt>FlagInterlaced</tt> is not set to 1, this element <bcp14>MUST</bcp14> be ignored.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>defined values:</t>
<table anchor="FieldOrderValues"><name>FieldOrder values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">progressive</td>
<td align="left">Interlaced frames.This frames. This value <bcp14>SHOULD</bcp14> be avoided, avoided; setting FlagInterlaced <tt>FlagInterlaced</tt> to 2 is sufficient.</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">tff</td>
<td align="left">Top field displayed first. Top field stored first.</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">undetermined</td>
<td align="left">Unknown field order.This order. This value <bcp14>SHOULD</bcp14> be avoided.</td>
</tr>

<tr>
<td align="left"><tt>6</tt></td>
<td align="left">bff</td>
<td align="left">Bottom field displayed first. Bottom field stored first.</td>
</tr>

<tr>
<td align="left"><tt>9</tt></td>
<td align="left">bff(swapped)</td> align="left">tff (interleaved)</td>
<td align="left">Top field displayed first. Fields are interleaved in storage with the top line of the top field stored first.</td>
</tr>

<tr>
<td align="left"><tt>14</tt></td>
<td align="left">tff(swapped)</td> align="left">bff (interleaved)</td>
<td align="left">Bottom field displayed first. Fields are interleaved in storage with the top line of the top field stored first.</td>
</tr>
</tbody>
</table>
<dl spacing="compact">
<dt>usage notes:</dt>
<dd>If FlagInterlaced is not set to 1, this Element <bcp14>MUST</bcp14> be ignored.</dd>
</dl>
<t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</section>

<section anchor="stereomode-element"><name>StereoMode Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x53B8 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\StereoMode</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>Stereo-3D video mode. There are some See <xref target="multi-planar-and-3d-videos"/> for more details details.</dd>
<dt>defined values:</dt>
<dd>See <xref target="StereoModeValues"/>. Additional values can be registered in the "Matroska Stereo Modes" registry defined in <xref target="multi-planar-and-3d-videos"></xref>.</dd> target="matroska-stereo-modes-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="StereoModeValues"><name>StereoMode values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">mono</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">side by side (left eye first)</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">top - bottom (right eye is first)</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">top - bottom (left eye is first)</td>
</tr>

<tr>
<td align="left"><tt>4</tt></td>
<td align="left">checkboard (right eye is first)</td>
</tr>

<tr>
<td align="left"><tt>5</tt></td>
<td align="left">checkboard (left eye is first)</td>
</tr>

<tr>
<td align="left"><tt>6</tt></td>
<td align="left">row interleaved (right eye is first)</td>
</tr>

<tr>
<td align="left"><tt>7</tt></td>
<td align="left">row interleaved (left eye is first)</td>
</tr>

<tr>
<td align="left"><tt>8</tt></td>
<td align="left">column interleaved (right eye is first)</td>
</tr>

<tr>
<td align="left"><tt>9</tt></td>
<td align="left">column interleaved (left eye is first)</td>
</tr>

<tr>
<td align="left"><tt>10</tt></td>
<td align="left">anaglyph (cyan/red)</td>
</tr>

<tr>
<td align="left"><tt>11</tt></td>
<td align="left">side by side (right eye first)</td>
</tr>

<tr>
<td align="left"><tt>12</tt></td>
<td align="left">anaglyph (green/magenta)</td>
</tr>

<tr>
<td align="left"><tt>13</tt></td>
<td align="left">both eyes laced in one Block (left eye is first)</td>
</tr>

<tr>
<td align="left"><tt>14</tt></td>
<td align="left">both eyes laced in one Block (right eye is first)</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="alphamode-element"><name>AlphaMode Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x53C0 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\AlphaMode</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>Indicate
<dd>Indicates whether the BlockAdditional Element <tt>BlockAdditional</tt> element with BlockAddID <tt>BlockAddID</tt> of &quot;1&quot; "1"
contains Alpha data, data as defined by to the Codec Mapping for the <tt>CodecID</tt>.
Undefined values (i.e., values other than 0 or 1) <bcp14>SHOULD NOT</bcp14> be used used, as the
behavior of known implementations is different (considered either as 0 or 1).</dd> different.</dd>
<dt>defined values:</dt>
<dd>See <xref target="AlphaModeValues"/>. Additional values can be registered in the "Matroska Alpha Modes" registry defined in <xref target="matroska-alpha-modes-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>defined values:</t>
<table anchor="AlphaModeValues"><name>AlphaMode values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">none</td>
<td align="left">The BlockAdditional Element <tt>BlockAdditional</tt> element with BlockAddID <tt>BlockAddID</tt> of &quot;1&quot; "1" does not exist or <bcp14>SHOULD NOT</bcp14> be considered as containing such data.</td>
</tr>
<tr>
<td align="left"><tt>1</tt></td>
<td align="left">present</td>
<td align="left">The BlockAdditional Element <tt>BlockAdditional</tt> element with BlockAddID <tt>BlockAddID</tt> of &quot;1&quot; "1" contains alpha channel data.</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="oldstereomode-element"><name>OldStereoMode Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x53B9 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\OldStereoMode</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>maxver:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>Bogus StereoMode <tt>StereoMode</tt> value used in old versions of libmatroska.</dd> <xref target="libmatroska"/>.</dd>
<dt>restrictions:</dt>
<dd>See <xref target="OldStereoModeValues"/>.</dd>
<dt>usage notes:</dt>
<dd>This element <bcp14>MUST NOT</bcp14> be used. It was an incorrect value used in libmatroska up to 0.9.0.</dd>
</dl>
<t>restrictions:</t>
<table anchor="OldStereoModeValues"><name>OldStereoMode values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">mono</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">right eye</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">left eye</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">both eyes</td>
</tr>
</tbody>
</table>
<dl spacing="compact">
<dt>usage notes:</dt>
<dd>This Element <bcp14>MUST NOT</bcp14> be used. It was an incorrect value used in libmatroska up to 0.9.0.</dd>
</dl>
</section>

<section anchor="pixelwidth-element"><name>PixelWidth Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xB0 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\PixelWidth</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Width of the encoded video frames in pixels.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="pixelheight-element"><name>PixelHeight Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xBA / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\PixelHeight</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Height of the encoded video frames in pixels.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="pixelcropbottom-element"><name>PixelCropBottom Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x54AA / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\PixelCropBottom</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The number of video pixels to remove at the bottom of the image.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="pixelcroptop-element"><name>PixelCropTop Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x54BB / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\PixelCropTop</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The number of video pixels to remove at the top of the image.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="pixelcropleft-element"><name>PixelCropLeft Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x54CC / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\PixelCropLeft</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The number of video pixels to remove on the left of the image.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="pixelcropright-element"><name>PixelCropRight Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x54DD / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\PixelCropRight</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The number of video pixels to remove on the right of the image.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="displaywidth-element"><name>DisplayWidth Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x54B0 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\DisplayWidth</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Width of the video frames to display. Applies to the video frame after cropping (PixelCrop* Elements).</dd>
<dt>notes:</dt>
<dd>See <xref target="DisplayWidthNotes"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>notes:</t>
<table anchor="DisplayWidthNotes"><name>DisplayWidth implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">default</td>
<td align="left">If the DisplayUnit of the same TrackEntry <tt>TrackEntry</tt> is 0, then the default value for DisplayWidth <tt>DisplayWidth</tt> is equal toPixelWidth to <tt>PixelWidth</tt> - PixelCropLeft <tt>PixelCropLeft</tt> - PixelCropRight, else <tt>PixelCropRight</tt>; else, there is no default value.</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="displayheight-element"><name>DisplayHeight Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x54BA / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\DisplayHeight</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Height of the video frames to display. Applies to the video frame after cropping (PixelCrop* Elements).</dd>
<dt>notes:</dt>
<dd>See <xref target="DisplayHeightNotes"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>notes:</t>
<table anchor="DisplayHeightNotes"><name>DisplayHeight implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">default</td>
<td align="left">If the DisplayUnit of the same TrackEntry <tt>TrackEntry</tt> is 0, then the default value for DisplayHeight <tt>DisplayHeight</tt> is equal toPixelHeight to <tt>PixelHeight</tt> - PixelCropTop <tt>PixelCropTop</tt> - PixelCropBottom, else <tt>PixelCropBottom</tt>; else, there is no default value.</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="displayunit-element"><name>DisplayUnit Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x54B2 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\DisplayUnit</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>How DisplayWidth &amp; DisplayHeight <tt>DisplayWidth</tt> and <tt>DisplayHeight</tt> are interpreted.</dd>
<dt>defined values:</dt>
<dd>See <xref target="DisplayUnitValues"/>. Additional values can be registered in the "Matroska Display Units" registry defined in <xref target="matroska-display-units-registry"/>.</dd>
</dl>
<t>restrictions:</t>
<table anchor="DisplayUnitValues"><name>DisplayUnit values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">pixels</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">centimeters</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">inches</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">display aspect ratio</td>
</tr>

<tr>
<td align="left"><tt>4</tt></td>
<td align="left">unknown</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="uncompressedfourcc-element"><name>UncompressedFourCC Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x2EB524 / binary</dd>
<dt>length:</dt>
<dd>4</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\UncompressedFourCC</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>see implementation notes
<dd>See <xref target="UncompressedFourCCNotes"/> / 1</dd>
<dt>definition:</dt>
<dd>Specify
<dd>Specifies the uncompressed pixel format used for the Track's <tt>Track</tt>'s data as a FourCC.
This value is similar in scope to the biCompression value of AVI's <tt>BITMAPINFO</tt> <xref target="AVIFormat"></xref>. target="AVIFormat"/>. There is no neither a definitive list of FourCC values, values nor an official registry. Some common values for YUV pixel formats can be found at <xref target="MSYUV8"></xref>, target="MSYUV8"/>, <xref target="MSYUV16"></xref> target="MSYUV16"/>, and <xref target="FourCC-YUV"></xref>. target="FourCC-YUV"/>. Some common values for uncompressed RGB pixel formats can be found at <xref target="MSRGB"></xref> target="MSRGB"/> and <xref target="FourCC-RGB"></xref>.</dd> target="FourCC-RGB"/>.</dd>
<dt>notes:</dt>
<dd>See <xref target="UncompressedFourCCNotes"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>notes:</t>
<table anchor="UncompressedFourCCNotes"><name>UncompressedFourCC implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">minOccurs</td>
<td align="left">UncompressedFourCC <bcp14>MUST</bcp14> be set (minOccurs=1) in TrackEntry, <tt>TrackEntry</tt> when the CodecID Element <tt>CodecID</tt> element of the TrackEntry <tt>TrackEntry</tt> is set to &quot;V_UNCOMPRESSED&quot;.</td> "V_UNCOMPRESSED".</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="colour-element"><name>Colour Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55B0 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Settings describing the colour color format.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="matrixcoefficients-element"><name>MatrixCoefficients Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55B1 / uinteger / 2</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MatrixCoefficients</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The Matrix Coefficients of the video used to derive luma and chroma values from red, green, and blue color primaries.
For clarity, the value and meanings for MatrixCoefficients <tt>MatrixCoefficients</tt> are adopted from Table 4 of <xref target="ITU-H.273"></xref>.</dd> target="ITU-H.273"/>.</dd>
<dt>restrictions:</dt>
<dd>See <xref target="MatrixCoefficientsValues"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="MatrixCoefficientsValues"><name>MatrixCoefficients values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">Identity</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">ITU-R BT.709</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">unspecified</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">reserved</td>
</tr>

<tr>
<td align="left"><tt>4</tt></td>
<td align="left">US FCC 73.682</td>
</tr>

<tr>
<td align="left"><tt>5</tt></td>
<td align="left">ITU-R BT.470BG</td>
</tr>

<tr>
<td align="left"><tt>6</tt></td>
<td align="left">SMPTE 170M</td>
</tr>

<tr>
<td align="left"><tt>7</tt></td>
<td align="left">SMPTE 240M</td>
</tr>

<tr>
<td align="left"><tt>8</tt></td>
<td align="left">YCoCg</td>
</tr>

<tr>
<td align="left"><tt>9</tt></td>
<td align="left">BT2020 Non-constant Luminance</td>
</tr>

<tr>
<td align="left"><tt>10</tt></td>
<td align="left">BT2020 Constant Luminance</td>
</tr>

<tr>
<td align="left"><tt>11</tt></td>
<td align="left">SMPTE ST 2085</td>
</tr>

<tr>
<td align="left"><tt>12</tt></td>
<td align="left">Chroma-derived Non-constant Luminance</td>
</tr>

<tr>
<td align="left"><tt>13</tt></td>
<td align="left">Chroma-derived Constant Luminance</td>
</tr>

<tr>
<td align="left"><tt>14</tt></td>
<td align="left">ITU-R BT.2100-0</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="bitsperchannel-element"><name>BitsPerChannel Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55B2 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\BitsPerChannel</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Number of decoded bits per channel. A value of 0 indicates that the BitsPerChannel <tt>BitsPerChannel</tt> is unspecified.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="chromasubsamplinghorz-element"><name>ChromaSubsamplingHorz Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55B3 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingHorz</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The amount number of pixels to remove in the Cr and Cb channels for every pixel not removed horizontally. Example: For video with 4:2:0 chroma subsampling, the ChromaSubsamplingHorz <tt>ChromaSubsamplingHorz</tt>
<bcp14>SHOULD</bcp14> be set to 1.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="chromasubsamplingvert-element"><name>ChromaSubsamplingVert Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55B4 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingVert</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The amount number of pixels to remove in the Cr and Cb channels for every pixel not removed vertically.
Example: For video with 4:2:0 chroma subsampling, the ChromaSubsamplingVert <tt>ChromaSubsamplingVert</tt>
<bcp14>SHOULD</bcp14> be set to 1.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="cbsubsamplinghorz-element"><name>CbSubsamplingHorz Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55B5 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingHorz</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The amount number of pixels to remove in the Cb channel for every pixel not removed horizontally.
This is additive with ChromaSubsamplingHorz. <tt>ChromaSubsamplingHorz</tt>.
Example: For video with 4:2:1 chroma
subsampling, the ChromaSubsamplingHorz <tt>ChromaSubsamplingHorz</tt> <bcp14>SHOULD</bcp14> be set to 1 1, and CbSubsamplingHorz <tt>CbSubsamplingHorz</tt> <bcp14>SHOULD</bcp14> be set to 1.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="cbsubsamplingvert-element"><name>CbSubsamplingVert Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55B6 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingVert</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The amount number of pixels to remove in the Cb channel for every pixel not removed vertically.
This is additive with ChromaSubsamplingVert.</dd>
</dl>
<t>stream copy: True <tt>ChromaSubsamplingVert</tt>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="chromasitinghorz-element"><name>ChromaSitingHorz Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55B7 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingHorz</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>How chroma is subsampled horizontally.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ChromaSitingHorzValues"/>. Additional values can be registered in the "Matroska Horizontal Chroma Sitings" registry defined in <xref target="matroska-horizontal-chroma-sitings-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="ChromaSitingHorzValues"><name>ChromaSitingHorz values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">unspecified</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">left collocated</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">half</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="chromasitingvert-element"><name>ChromaSitingVert Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55B8 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingVert</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>How chroma is subsampled vertically.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ChromaSitingVertValues"/>. Additional values can be registered in the "Matroska Vertical Chroma Sitings" registry defined in <xref target="matroska-vertical-chroma-sitings-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="ChromaSitingVertValues"><name>ChromaSitingVert values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">unspecified</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">top collocated</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">half</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="range-element"><name>Range anchor="color-range-element"><name>Color Range Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55B9 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\Range</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Clipping of the color ranges.</dd>
<dt>defined values:</dt>
<dd>See <xref target="RangeValues"/>. Additional values can be registered in the "Matroska Color Ranges" registry defined in <xref target="matroska-color-ranges-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="RangeValues"><name>Range values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">unspecified</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">broadcast range</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">full range (no clipping)</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">defined by MatrixCoefficients / TransferCharacteristics</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="transfercharacteristics-element"><name>TransferCharacteristics Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55BA / uinteger / 2</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\TransferCharacteristics</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The transfer characteristics of the video. For clarity,
the value and meanings for TransferCharacteristics <tt>TransferCharacteristics</tt> are adopted from Table 3 of <xref target="ITU-H.273"></xref>.</dd> target="ITU-H.273"/>.</dd>
<dt>restrictions:</dt>
<dd>See <xref target="TransferCharacteristicsValues"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="TransferCharacteristicsValues"><name>TransferCharacteristics values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">reserved</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">ITU-R BT.709</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">unspecified</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">reserved2</td>
</tr>

<tr>
<td align="left"><tt>4</tt></td>
<td align="left">Gamma 2.2 curve - BT.470M</td>
</tr>

<tr>
<td align="left"><tt>5</tt></td>
<td align="left">Gamma 2.8 curve - BT.470BG</td>
</tr>

<tr>
<td align="left"><tt>6</tt></td>
<td align="left">SMPTE 170M</td>
</tr>

<tr>
<td align="left"><tt>7</tt></td>
<td align="left">SMPTE 240M</td>
</tr>

<tr>
<td align="left"><tt>8</tt></td>
<td align="left">Linear</td>
</tr>

<tr>
<td align="left"><tt>9</tt></td>
<td align="left">Log</td>
</tr>

<tr>
<td align="left"><tt>10</tt></td>
<td align="left">Log Sqrt</td>
</tr>

<tr>
<td align="left"><tt>11</tt></td>
<td align="left">IEC 61966-2-4</td>
</tr>

<tr>
<td align="left"><tt>12</tt></td>
<td align="left">ITU-R BT.1361 Extended Colour Gamut</td>
</tr>

<tr>
<td align="left"><tt>13</tt></td>
<td align="left">IEC 61966-2-1</td>
</tr>

<tr>
<td align="left"><tt>14</tt></td>
<td align="left">ITU-R BT.2020 10 bit</td>
</tr>

<tr>
<td align="left"><tt>15</tt></td>
<td align="left">ITU-R BT.2020 12 bit</td>
</tr>

<tr>
<td align="left"><tt>16</tt></td>
<td align="left">ITU-R BT.2100 Perceptual Quantization</td>
</tr>

<tr>
<td align="left"><tt>17</tt></td>
<td align="left">SMPTE ST 428-1</td>
</tr>

<tr>
<td align="left"><tt>18</tt></td>
<td align="left">ARIB STD-B67 (HLG)</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="primaries-element"><name>Primaries Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x55BB / uinteger / 2</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\Primaries</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The colour color primaries of the video. For clarity,
the value and meanings for Primaries <tt>Primaries</tt> are adopted from Table 2 of <xref target="ITU-H.273"></xref>.</dd> target="ITU-H.273"/>.</dd>
<dt>restrictions:</dt>
<dd>See <xref target="PrimariesValues"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="PrimariesValues"><name>Primaries values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">reserved</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">ITU-R BT.709</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">unspecified</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">reserved2</td>
</tr>

<tr>
<td align="left"><tt>4</tt></td>
<td align="left">ITU-R BT.470M</td>
</tr>

<tr>
<td align="left"><tt>5</tt></td>
<td align="left">ITU-R BT.470BG - BT.601 625</td>
</tr>

<tr>
<td align="left"><tt>6</tt></td>
<td align="left">ITU-R BT.601 525 - SMPTE 170M</td>
</tr>

<tr>
<td align="left"><tt>7</tt></td>
<td align="left">SMPTE 240M</td>
</tr>

<tr>
<td align="left"><tt>8</tt></td>
<td align="left">FILM</td>
</tr>

<tr>
<td align="left"><tt>9</tt></td>
<td align="left">ITU-R BT.2020</td>
</tr>

<tr>
<td align="left"><tt>10</tt></td>
<td align="left">SMPTE ST 428-1</td>
</tr>

<tr>
<td align="left"><tt>11</tt></td>
<td align="left">SMPTE RP 432-2</td>
</tr>

<tr>
<td align="left"><tt>12</tt></td>
<td align="left">SMPTE EG 432-2</td>
</tr>

<tr>
<td align="left"><tt>22</tt></td>
<td align="left">EBU Tech. 3213-E - JEDEC P22 phosphors</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="maxcll-element"><name>MaxCLL Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55BC / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MaxCLL</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Maximum brightness of a single pixel (Maximum Content Light Level)
in candelas per square meter (cd/m<sup>2</sup>).</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="maxfall-element"><name>MaxFALL Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55BD / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MaxFALL</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Maximum brightness of a single full frame (Maximum Frame-Average Light Level)
in candelas per square meter (cd/m<sup>2</sup>).</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="masteringmetadata-element"><name>MasteringMetadata Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D0 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>SMPTE 2086 mastering data.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="primaryrchromaticityx-element"><name>PrimaryRChromaticityX Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D1 / float</dd>
<dt>range:</dt>
<dd>0x0p+0-0x1p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\PrimaryRChromaticityX</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Red X chromaticity coordinate, as defined by <xref target="CIE-1931"></xref>.</dd>
</dl>
<t>stream copy: True target="CIE-1931"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="primaryrchromaticityy-element"><name>PrimaryRChromaticityY Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D2 / float</dd>
<dt>range:</dt>
<dd>0x0p+0-0x1p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\PrimaryRChromaticityY</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Red Y chromaticity coordinate, as defined by <xref target="CIE-1931"></xref>.</dd>
</dl>
<t>stream copy: True target="CIE-1931"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="primarygchromaticityx-element"><name>PrimaryGChromaticityX Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D3 / float</dd>
<dt>range:</dt>
<dd>0x0p+0-0x1p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\PrimaryGChromaticityX</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Green X chromaticity coordinate, as defined by <xref target="CIE-1931"></xref>.</dd>
</dl>
<t>stream copy: True target="CIE-1931"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="primarygchromaticityy-element"><name>PrimaryGChromaticityY Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D4 / float</dd>
<dt>range:</dt>
<dd>0x0p+0-0x1p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\PrimaryGChromaticityY</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Green Y chromaticity coordinate, as defined by <xref target="CIE-1931"></xref>.</dd>
</dl>
<t>stream copy: True target="CIE-1931"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="primarybchromaticityx-element"><name>PrimaryBChromaticityX Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D5 / float</dd>
<dt>range:</dt>
<dd>0x0p+0-0x1p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\PrimaryBChromaticityX</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Blue X chromaticity coordinate, as defined by <xref target="CIE-1931"></xref>.</dd>
</dl>
<t>stream copy: True target="CIE-1931"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="primarybchromaticityy-element"><name>PrimaryBChromaticityY Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D6 / float</dd>
<dt>range:</dt>
<dd>0x0p+0-0x1p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\PrimaryBChromaticityY</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Blue Y chromaticity coordinate, as defined by <xref target="CIE-1931"></xref>.</dd>
</dl>
<t>stream copy: True target="CIE-1931"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="whitepointchromaticityx-element"><name>WhitePointChromaticityX Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D7 / float</dd>
<dt>range:</dt>
<dd>0x0p+0-0x1p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\WhitePointChromaticityX</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>White X chromaticity coordinate, as defined by <xref target="CIE-1931"></xref>.</dd>
</dl>
<t>stream copy: True target="CIE-1931"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="whitepointchromaticityy-element"><name>WhitePointChromaticityY Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D8 / float</dd>
<dt>range:</dt>
<dd>0x0p+0-0x1p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\WhitePointChromaticityY</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>White Y chromaticity coordinate, as defined by <xref target="CIE-1931"></xref>.</dd>
</dl>
<t>stream copy: True target="CIE-1931"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="luminancemax-element"><name>LuminanceMax Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55D9 / float</dd>
<dt>range:</dt>
<dd>&gt;= 0x0p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\LuminanceMax</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Maximum luminance. Represented in candelas per square meter (cd/m<sup>2</sup>).</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="luminancemin-element"><name>LuminanceMin Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x55DA / float</dd>
<dt>range:</dt>
<dd>&gt;= 0x0p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\LuminanceMin</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Minimum luminance. Represented in candelas per square meter (cd/m<sup>2</sup>).</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="projection-element"><name>Projection Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x7670 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Projection</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Describes the video projection details. Used to render spherical, spherical or VR videos or flipping to flip videos horizontally/vertically.</dd>
</dl>
<t>stream copy: True horizontally or vertically.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="projectiontype-element"><name>ProjectionType Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x7671 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Projection\ProjectionType</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Describes the projection used for this video track.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ProjectionTypeValues"/>. Additional values can be registered in the "Matroska Projection Types" registry defined in <xref target="matroska-projection-types-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="ProjectionTypeValues"><name>ProjectionType values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">rectangular</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">equirectangular</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">cubemap</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">mesh</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="projectionprivate-element"><name>ProjectionPrivate Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x7672 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPrivate</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Private data that only applies to a specific projection.</dd>
</dl>

<ul spacing="compact">
<li>If <tt>ProjectionType</tt> equals 0 (Rectangular), (rectangular),
 then this element <bcp14>MUST NOT</bcp14> be present.</li>
<li>If <tt>ProjectionType</tt> equals 1 (Equirectangular), (equirectangular), then this element <bcp14>MUST</bcp14> be present and contain the same binary data that would be stored inside
  an ISOBMFF Equirectangular Projection Box ('equi').</li> ("equi").</li>
<li>If <tt>ProjectionType</tt> equals 2 (Cubemap), (cubemap), then this element <bcp14>MUST</bcp14> be present and contain the same binary data that would be stored
  inside an ISOBMFF Cubemap Projection Box ('cbmp').</li> ("cbmp").</li>
<li>If <tt>ProjectionType</tt> equals 3 (Mesh), (mesh), then this element <bcp14>MUST</bcp14> be present and contain the same binary data that would be stored inside
   an ISOBMFF Mesh Projection Box ('mshp').</li> ("mshp").</li>
</ul>

<dl spacing="compact">
<dt>usage notes:</dt>
<dd>ISOBMFF box size and fourcc FourCC fields are not included in the binary data,
but the FullBox version and flag fields are. This is to avoid
redundant framing information while preserving versioning and semantics between the two container formats.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="projectionposeyaw-element"><name>ProjectionPoseYaw Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x7673 / float / 0x0p+0</dd>
<dt>range:</dt>
<dd>&gt;= -0xB4p+0, &lt;= 0xB4p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseYaw</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Specifies a yaw rotation to the projection.</dd>
</dl>
<t>Value projection. Value represents a clockwise rotation, in degrees, around the up vector. This rotation must be applied
before any <tt>ProjectionPosePitch</tt> or <tt>ProjectionPoseRoll</tt> rotations.
The value of this element <bcp14>MUST</bcp14> be in the -180 to 180 degree range, both included.</t> inclusive.</dd>
</dl>
<t>Setting <tt>ProjectionPoseYaw</tt> to 180 or -180 degrees, degrees with the <tt>ProjectionPoseRoll</tt> and <tt>ProjectionPosePitch</tt> set to 0 degrees flips the image horizontally.</t>
<t>stream copy: True

<dl spacing="compact">
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="projectionposepitch-element"><name>ProjectionPosePitch Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x7674 / float / 0x0p+0</dd>
<dt>range:</dt>
<dd>&gt;= -0x5Ap+0, &lt;= 0x5Ap+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPosePitch</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Specifies a pitch rotation to the projection.</dd>
</dl>
<t>Value projection. Value represents a counter-clockwise rotation, in degrees, around the right vector. This rotation must be applied
after the <tt>ProjectionPoseYaw</tt> rotation and before the <tt>ProjectionPoseRoll</tt> rotation.
The value of this element <bcp14>MUST</bcp14> be in the -90 to 90 degree range, both included.</t>
<t>stream copy: True inclusive.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="projectionposeroll-element"><name>ProjectionPoseRoll Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x7675 / float / 0x0p+0</dd>
<dt>range:</dt>
<dd>&gt;= -0xB4p+0, &lt;= 0xB4p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseRoll</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Specifies a roll rotation to the projection.</dd>
</dl>
<t>Value projection. Value represents a
counter-clockwise rotation, in degrees, around the forward vector. This
rotation must be applied after the <tt>ProjectionPoseYaw</tt> and
<tt>ProjectionPosePitch</tt> rotations.  The value of this element
<bcp14>MUST</bcp14> be in the -180 to 180 degree range, both included.</t>
<t>Setting inclusive. Setting <tt>ProjectionPoseRoll</tt> to 180 or -180 degrees, the degrees and
<tt>ProjectionPoseYaw</tt> to 180 or -180 degrees with
<tt>ProjectionPosePitch</tt> set to 0 degrees flips the image vertically.</t>
<t>Setting vertically.
Setting <tt>ProjectionPoseRoll</tt> to 180 or -180 degrees, degrees with the
<tt>ProjectionPoseYaw</tt> and <tt>ProjectionPosePitch</tt> set to 0 degrees
flips the image horizontally and vertically.</t>
<t>stream copy: True vertically.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>
</section>

<section anchor="audio-element"><name>Audio Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE1 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Audio</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Audio settings.</dd>
</dl>

<section anchor="samplingfrequency-element"><name>SamplingFrequency Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0xB5 / float / 0x1.f4p+12</dd>
<dt>range:</dt>
<dd>&gt; 0x0p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Audio\SamplingFrequency</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Sampling frequency in Hz.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="outputsamplingfrequency-element"><name>OutputSamplingFrequency Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x78B5 / float</dd>
<dt>range:</dt>
<dd>&gt; 0x0p+0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Audio\OutputSamplingFrequency</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Real output sampling frequency in Hz (used that is used for SBR techniques).</dd> Spectral Band Replication (SBR) techniques.</dd>
<dt>notes:</dt>
<dd>See <xref target="OutputSamplingFrequencyNotes"/>.</dd>
</dl>
<t>notes:</t>
<table anchor="OutputSamplingFrequencyNotes"><name>OutputSamplingFrequency implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">default</td>
<td align="left">The default value for OutputSamplingFrequency <tt>OutputSamplingFrequency</tt> of the same TrackEntry <tt>TrackEntry</tt> is equal to the SamplingFrequency.</td> <tt>SamplingFrequency</tt>.</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="channels-element"><name>Channels Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x9F / uinteger / 1</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Audio\Channels</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Numbers of channels in the track.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="bitdepth-element"><name>BitDepth Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6264 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Audio\BitDepth</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Bits per sample, mostly used for PCM.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>
</section>

<section anchor="trackoperation-element"><name>TrackOperation Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE2 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOperation</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>Operation that needs to be applied on tracks to create this virtual track. For more details look at details, see <xref target="track-operation"></xref>.</dd>
</dl>
<t>stream copy: True target="track-operation"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>

<section anchor="trackcombineplanes-element"><name>TrackCombinePlanes Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE3 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>Contains the list of all video plane tracks that need to be combined to create this 3D track</dd>
</dl>
<t>stream copy: True track.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="trackplane-element"><name>TrackPlane Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE4 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\TrackPlane</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>Contains a video plane track that need needs to be combined to create this 3D track</dd>
</dl>
<t>stream copy: True track.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="trackplaneuid-element"><name>TrackPlaneUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE5 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\TrackPlane\TrackPlaneUID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>The trackUID <tt>TrackUID</tt> number of the track representing the plane.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="trackplanetype-element"><name>TrackPlaneType Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE6 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\TrackPlane\TrackPlaneType</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>The kind of plane this track corresponds to.</dd>
<dt>defined values:</dt>
<dd>See <xref target="TrackPlaneTypeValues"/>. Additional values can be registered in the "Matroska Track Plane Types" registry defined in <xref target="matroska-track-plane-types-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="TrackPlaneTypeValues"><name>TrackPlaneType values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">left eye</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">right eye</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">background</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="trackjoinblocks-element"><name>TrackJoinBlocks Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xE9 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>Contains the list of all tracks whose Blocks <tt>Blocks</tt> need to be combined to create this virtual track</dd>
</dl>
<t>stream copy: True track.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="trackjoinuid-element"><name>TrackJoinUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xED / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks\TrackJoinUID</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>The trackUID <tt>TrackUID</tt> number of a track whose blocks are used to create this virtual track.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>
</section>

<section anchor="contentencodings-element"><name>ContentEncodings Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6D80 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Settings for several content encoding mechanisms like compression or encryption.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>

<section anchor="contentencoding-element"><name>ContentEncoding Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6240 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Settings for one content encoding like compression or encryption.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="contentencodingorder-element"><name>ContentEncodingOrder Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x5031 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncodingOrder</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Tell in which
<dd>Defines the order to apply each <tt>ContentEncoding</tt> of the <tt>ContentEncodings</tt>.
The decoder/demuxer <bcp14>MUST</bcp14> start with the <tt>ContentEncoding</tt> with the highest <tt>ContentEncodingOrder</tt> and work its way down to the <tt>ContentEncoding</tt> with the lowest <tt>ContentEncodingOrder</tt>.
This value <bcp14>MUST</bcp14> be unique over for each <tt>ContentEncoding</tt> found in the <tt>ContentEncodings</tt> of this <tt>TrackEntry</tt>.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="contentencodingscope-element"><name>ContentEncodingScope Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x5032 / uinteger / 1</dd>
<dt>range:</dt>
<dd>not 0 (0x1-0x8000000000000000)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncodingScope</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>A bit field that describes which Elements elements have been modified in this way. Values (big-endian) can be OR'ed.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ContentEncodingScopeValues"/>. Additional values can be registered in the "Matroska Content Encoding Scopes" registry defined in <xref target="matroska-content-encoding-scopes-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>defined values:</t>
<table anchor="ContentEncodingScopeValues"><name>ContentEncodingScope values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>1</tt></td> align="left"><tt>0x1</tt></td>
<td align="left">Block</td>
<td align="left">All frame contents, excluding lacing data.</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td> align="left"><tt>0x2</tt></td>
<td align="left">Private</td>
<td align="left">The track's <tt>CodecPrivate</tt> data.</td>
</tr>

<tr>
<td align="left"><tt>4</tt></td> align="left"><tt>0x4</tt></td>
<td align="left">Next</td>
<td align="left">The next ContentEncoding (next <tt>ContentEncodingOrder</tt>. Either <tt>ContentEncodingOrder</tt>; the data inside <tt>ContentCompression</tt> and/or <tt>ContentEncryption</tt>).This <tt>ContentEncryption</tt>). This value <bcp14>SHOULD NOT</bcp14> be used used, as it's not supported by players.</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="contentencodingtype-element"><name>ContentEncodingType Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x5033 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncodingType</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>A value describing what the kind of transformation that is applied.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ContentEncodingTypeValues"/>. Additional values can be registered in the "Matroska Content Encoding Types" registry defined in <xref target="matroska-content-encoding-types-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>restrictions:</t>
<table anchor="ContentEncodingTypeValues"><name>ContentEncodingType values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">Compression</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">Encryption</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="contentcompression-element"><name>ContentCompression Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x5034 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentCompression</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Settings describing the compression used.
This Element element <bcp14>MUST</bcp14> be present if the value of ContentEncodingType <tt>ContentEncodingType</tt> is 0 and absent otherwise.
Each block <bcp14>MUST</bcp14> be decompressable decompressable, even if no previous block is available in order not to not prevent seeking.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="contentcompalgo-element"><name>ContentCompAlgo Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x4254 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentCompression\ContentCompAlgo</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The compression algorithm used.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ContentCompAlgoValues"/>. Additional values can be registered in the "Matroska Compression Algorithms" registry defined in <xref target="matroska-compression-algorithms-registry"/>.</dd>
<dt>usage notes:</dt>
<dd>Compression method "1" (bzlib) and "2" (lzo1x) lack proper documentation on the format, which limits implementation possibilities. Due to licensing conflicts on commonly available libraries' compression methods, "2" (lzo1x) does not offer widespread interoperability. A <tt>Matroska Writer</tt> <bcp14>SHOULD NOT</bcp14> use these compression methods by default. A <tt>Matroska Reader</tt> <bcp14>MAY</bcp14> support methods "1" and "2" and <bcp14>SHOULD</bcp14> support other methods.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>defined values:</t>
<table anchor="ContentCompAlgoValues"><name>ContentCompAlgo values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">zlib</td>
<td align="left">zlib compression <xref target="RFC1950"></xref>.</td> target="RFC1950"/>.</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">bzlib</td>
<td align="left">bzip2 compression <xref target="BZIP2"></xref>, target="BZIP2"/> <bcp14>SHOULD NOT</bcp14> be used; see usage notes.</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">lzo1x</td>
<td align="left">Lempel-Ziv-Oberhumer compression <xref target="LZO"></xref>, target="LZO"/> <bcp14>SHOULD NOT</bcp14> be used; see usage notes.</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">Header Stripping</td>
<td align="left">Octets in <tt>ContentCompSettings</tt> (<xref target="contentcompsettings-element"></xref>) target="contentcompsettings-element"/>) have been stripped from each frame.</td>
</tr>
</tbody>
</table>
<dl spacing="compact">
<dt>usage notes:</dt>
<dd>Compression method &quot;1&quot; (bzlib) and &quot;2&quot; (lzo1x) are lacking proper documentation on the format which limits implementation possibilities.
Due to licensing conflicts on commonly available libraries compression methods &quot;2&quot; (lzo1x) does not offer widespread interoperability.
A Matroska Writer <bcp14>SHOULD NOT</bcp14> use these compression methods by default.
A Matroska Reader <bcp14>MAY</bcp14> support methods &quot;1&quot; and &quot;2&quot; as possible, and <bcp14>SHOULD</bcp14> support other methods.</dd>
</dl>
<t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</section>

<section anchor="contentcompsettings-element"><name>ContentCompSettings Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4255 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentCompression\ContentCompSettings</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Settings that might be needed by the decompressor. For Header Stripping (<tt>ContentCompAlgo</tt>=3),
the bytes that were removed from the beginning of each frames frame of the track.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="contentencryption-element"><name>ContentEncryption Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x5035 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Settings describing the encryption used.
This Element element <bcp14>MUST</bcp14> be present if the value of <tt>ContentEncodingType</tt> is 1 (encryption) and <bcp14>MUST</bcp14> be ignored otherwise.
A Matroska Player <tt>Matroska Player</tt> <bcp14>MAY</bcp14> support encryption.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="contentencalgo-element"><name>ContentEncAlgo Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x47E1 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption\ContentEncAlgo</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The encryption algorithm used.</dd>
<dt>defined values:</dt>
<dd>See <xref target="ContentEncAlgoValues"/>. Additional values can be registered in the "Matroska Encryption Algorithms" registry defined in <xref target="matroska-encryption-algorithms-registry"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>defined values:</t>
<table anchor="ContentEncAlgoValues"><name>ContentEncAlgo values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">Not encrypted</td>
<td align="left">The data are not encrypted.</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">DES</td>
<td align="left">Data Encryption Standard (DES) <xref target="FIPS.46-3"></xref>.This target="FIPS46-3"/>. This value <bcp14>SHOULD</bcp14> be avoided.</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">3DES</td>
<td align="left">Triple Data Encryption Algorithm <xref target="SP.800-67"></xref>.This target="SP800-67"/>. This value <bcp14>SHOULD</bcp14> be avoided.</td>
</tr>

<tr>
<td align="left"><tt>3</tt></td>
<td align="left">Twofish</td>
<td align="left">Twofish Encryption Algorithm <xref target="Twofish"></xref>.</td> target="Twofish"/>.</td>
</tr>

<tr>
<td align="left"><tt>4</tt></td>
<td align="left">Blowfish</td>
<td align="left">Blowfish Encryption Algorithm <xref target="Blowfish"></xref>.This target="Blowfish"/>. This value <bcp14>SHOULD</bcp14> be avoided.</td>
</tr>

<tr>
<td align="left"><tt>5</tt></td>
<td align="left">AES</td>
<td align="left">Advanced Encryption Standard (AES) <xref target="FIPS.197"></xref>.</td> target="FIPS197"/>.</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="contentenckeyid-element"><name>ContentEncKeyID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x47E2 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption\ContentEncKeyID</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>For public key algorithms this is algorithms, the ID of the public key that the data was encrypted with.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="contentencaessettings-element"><name>ContentEncAESSettings Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x47E7 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption\ContentEncAESSettings</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>Settings describing the encryption algorithm used.</dd>
<dt>notes:</dt>
<dd>See <xref target="ContentEncAESSettingsNotes"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>notes:</t>
<table anchor="ContentEncAESSettingsNotes"><name>ContentEncAESSettings implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">maxOccurs</td>
<td align="left">ContentEncAESSettings <bcp14>MUST NOT</bcp14> be set (maxOccurs=0) if ContentEncAlgo is not AES (5).</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>

<section anchor="aessettingsciphermode-element"><name>AESSettingsCipherMode Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x47E8 / uinteger</dd>
<dt>range:</dt>
<dd>not 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption\ContentEncAESSettings\AESSettingsCipherMode</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The AES cipher mode used in the encryption.</dd>
<dt>defined values:</dt>
<dd>See <xref target="AESSettingsCipherModeValues"/>. Additional values can be registered in the "Matroska AES Cipher Modes" registry defined in <xref target="matroska-aes-cipher-modes-registry"/>.</dd>
<dt>notes:</dt>
<dd>See <xref target="AESSettingsCipherModeNotes"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"/>)</dd>
</dl>
<t>defined values:</t>
<table anchor="AESSettingsCipherModeValues"><name>AESSettingsCipherMode values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>1</tt></td>
<td align="left">AES-CTR</td>
<td align="left">Counter <xref target="SP.800-38A"></xref>.</td> target="SP800-38A"/></td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">AES-CBC</td>
<td align="left">Cipher Block Chaining <xref target="SP.800-38A"></xref>.</td> target="SP800-38A"/></td>
</tr>
</tbody>
</table><t>notes:</t>
<table
</table><table anchor="AESSettingsCipherModeNotes"><name>AESSettingsCipherMode implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">maxOccurs</td>
<td align="left">AESSettingsCipherMode <bcp14>MUST NOT</bcp14> be set (maxOccurs=0) if ContentEncAlgo is not AES (5).</td>
</tr>
</tbody>
</table><t>stream copy: True (<xref target="stream-copy"></xref>)</t>
</table>
</section>
</section>
</section>
</section>

<section anchor="cues-element"><name>Cues Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x1C53BB6B / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>see implementation notes
<dd>See <xref target="CuesNotes"/> / 1</dd>
<dt>definition:</dt>
<dd>A Top-Level Element <tt>Top-Level Element</tt> to speed seeking access.  All entries are
local to the Segment.</dd> <tt>Segment</tt>.</dd>
<dt>notes:</dt>
<dd>See <xref target="CuesNotes"/>.</dd>
</dl>
<t>notes:</t>
<table anchor="CuesNotes"><name>Cues implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">minOccurs</td>
<td align="left">This Element element <bcp14>SHOULD</bcp14> be set when the Segment <tt>Segment</tt> is not transmitted as a live stream; see <xref target="livestreaming"></xref>.</td> target="livestreaming"/>.</td>
</tr>
</tbody>
</table>
<section anchor="cuepoint-element"><name>CuePoint Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xBB / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Contains all information relative to a seek point in the Segment.</dd> <tt>Segment</tt>.</dd>
</dl>

<section anchor="cuetime-element"><name>CueTime Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xB3 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTime</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Absolute timestamp of the seek point, expressed in Matroska Ticks -- i.e., in nanoseconds; Segment Ticks, which are based on <tt>TimestampScale</tt>; see <xref target="timestamp-ticks"></xref>.</dd> target="timestamp-ticks"/>.</dd>
</dl>
</section>

<section anchor="cuetrackpositions-element"><name>CueTrackPositions Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xB7 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Contain
<dd>Contains positions for different tracks corresponding to the timestamp.</dd>
</dl>

<section anchor="cuetrack-element"><name>CueTrack Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xF7 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueTrack</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The track for which a position is given.</dd>
</dl>
</section>

<section anchor="cueclusterposition-element"><name>CueClusterPosition Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xF1 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueClusterPosition</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The Segment Position <tt>Segment Position</tt> (<xref target="segment-position"></xref>) target="segment-position"/>) of the Cluster <tt>Cluster</tt> containing the associated Block.</dd> <tt>Block</tt>.</dd>
</dl>
</section>

<section anchor="cuerelativeposition-element"><name>CueRelativePosition Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xF0 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueRelativePosition</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The relative position inside the Cluster <tt>Cluster</tt> of the referenced SimpleBlock <tt>SimpleBlock</tt> or BlockGroup <tt>BlockGroup</tt>
with 0 being the first possible position for an Element element inside that Cluster.</dd> <tt>Cluster</tt>.</dd>
</dl>
</section>

<section anchor="cueduration-element"><name>CueDuration Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xB2 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueDuration</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The duration of the block, expressed in Segment Ticks Ticks, which is are based on TimestampScale; <tt>TimestampScale</tt>; see <xref target="timestamp-ticks"></xref>. target="timestamp-ticks"/>.
If missing, the track's DefaultDuration <tt>DefaultDuration</tt> does not apply and no duration information is available in terms of the cues.</dd>
</dl>
</section>

<section anchor="cueblocknumber-element"><name>CueBlockNumber Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x5378 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueBlockNumber</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Number of the Block <tt>Block</tt> in the specified Cluster.</dd> <tt>Cluster</tt>.</dd>
</dl>
</section>

<section anchor="cuecodecstate-element"><name>CueCodecState Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0xEA / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueCodecState</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>The Segment Position <tt>Segment Position</tt> (<xref target="segment-position"></xref>) target="segment-position"/>) of the
Codec State corresponding to this Cue Element. <tt>Cues</tt> element. 0 means that the
data is taken from the initial Track Entry.</dd> <tt>TrackEntry</tt>.</dd>
</dl>
</section>

<section anchor="cuereference-element"><name>CueReference Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xDB / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueReference</tt></dd>
<dt>minver:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>The Clusters <tt>Clusters</tt> containing the referenced Blocks.</dd> <tt>Blocks</tt>.</dd>
</dl>
</section>

<section anchor="cuereftime-element"><name>CueRefTime Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x96 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefTime</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>minver:</dt>
<dd>2</dd>
<dt>definition:</dt>
<dd>Timestamp of the referenced Block, <tt>Block</tt>, expressed in Matroska Segment Ticks -- i.e., in nanoseconds; which is based on <tt>TimestampScale</tt>; see <xref target="timestamp-ticks"></xref>.</dd> target="timestamp-ticks"/>.</dd>
</dl>
</section>
</section>
</section>
</section>

<section anchor="attachments-element"><name>Attachments Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x1941A469 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Contain
<dd>Contains attached files.</dd>
</dl>

<section anchor="attachedfile-element"><name>AttachedFile Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x61A7 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>An attached file.</dd>
</dl>

<section anchor="filedescription-element"><name>FileDescription Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x467E / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile\FileDescription</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A human-friendly name for the attached file.</dd>
</dl>
</section>

<section anchor="filename-element"><name>FileName Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x466E / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile\FileName</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Filename of the attached file.</dd>
</dl>
</section>

<section anchor="filemediatype-element"><name>FileMediaType Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4660 / string</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile\FileMediaType</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Media type of the file following the format described in <xref target="RFC6838"></xref> format.</dd>
</dl>
<t>stream copy: True target="RFC6838"/>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="filedata-element"><name>FileData Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x465C / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile\FileData</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The data of the file.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="fileuid-element"><name>FileUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x46AE / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile\FileUID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Unique ID
<dd>UID representing the file, as random as possible.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>
</section>
</section>

<section anchor="chapters-element"><name>Chapters Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x1043A770 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
</dl>
<t>recurring: True</t>

<dl spacing="compact">
<dt>recurring:</dt>
<dd>True</dd>
<dt>definition:</dt>
<dd>A system to define basic menus and partition data.
For more detailed information, look at the Chapters explanation in see <xref target="chapters"></xref>.</dd> target="chapters"/>.</dd>
</dl>

<section anchor="editionentry-element"><name>EditionEntry Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x45B9 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Contains all information about a Segment <tt>Segment</tt> edition.</dd>
</dl>

<section anchor="editionuid-element"><name>EditionUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x45BC / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\EditionUID</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A unique ID to identify UID that identifies the edition. It's useful for tagging an edition.</dd>
</dl>
<t>stream copy: True
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="editionflagdefault-element"><name>EditionFlagDefault Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x45DB / uinteger / 0</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\EditionFlagDefault</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Set to 1 if the edition <bcp14>SHOULD</bcp14> be used as the default one.</dd>
</dl>
</section>

<section anchor="editionflagordered-element"><name>EditionFlagOrdered Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x45DD / uinteger / 0</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\EditionFlagOrdered</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Set to 1 if the chapters can be defined multiple times and the order to play them is enforced; see <xref target="editionflagordered"></xref>.</dd> target="editionflagordered"/>.</dd>
</dl>
</section>

<section anchor="chapteratom-element"><name>ChapterAtom Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0xB6 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
</dl>
<t>recursive: True</t>

<dl spacing="compact">
<dt>recursive:</dt>
<dd>True</dd>
<dt>definition:</dt>
<dd>Contains the atom information to use as the chapter atom (apply (applies to all tracks).</dd>
</dl>

<section anchor="chapteruid-element"><name>ChapterUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x73C4 / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterUID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>A unique ID to identify UID that identifies the Chapter.</dd>
</dl>
<t>stream copy: True <tt>Chapter</tt>.</dd>
<dt>stream copy:</dt>
<dd>True (<xref target="stream-copy"></xref>)</t> target="stream-copy"/>)</dd>
</dl>
</section>

<section anchor="chapterstringuid-element"><name>ChapterStringUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x5654 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterStringUID</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>3</dd>
<dt>definition:</dt>
<dd>A unique string ID to identify that identifies the Chapter. <tt>Chapter</tt>.
For example example, it is used as the storage for <xref target="WebVTT"></xref> cue identifier values.</dd> values <xref target="WebVTT"/>.</dd>
</dl>
</section>

<section anchor="chaptertimestart-element"><name>ChapterTimeStart Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x91 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTimeStart</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Timestamp of the start of Chapter, <tt>Chapter</tt>, expressed in Matroska Ticks -- i.e., in nanoseconds; see <xref target="timestamp-ticks"></xref>.</dd> target="timestamp-ticks"/>.</dd>
</dl>
</section>

<section anchor="chaptertimeend-element"><name>ChapterTimeEnd Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x92 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTimeEnd</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>see implementation notes
<dd>See <xref target="ChapterTimeEndNotes"/> / 1</dd>
<dt>definition:</dt>
<dd>Timestamp of the end of Chapter timestamp excluded, <tt>Chapter</tt> (timestamp excluded), expressed in Matroska Ticks -- i.e., in nanoseconds; see <xref target="timestamp-ticks"></xref>. target="timestamp-ticks"/>.
The value <bcp14>MUST</bcp14> be greater than or equal to the <tt>ChapterTimeStart</tt> of the same <tt>ChapterAtom</tt>.</dd>
<dt>usage notes:</dt>
<dd>The
<dd>With the <tt>ChapterTimeEnd</tt> timestamp value being excluded, it <bcp14>MUST</bcp14> take in into account the duration of
the last frame it includes, especially for the <tt>ChapterAtom</tt> using the last frames of the <tt>Segment</tt>.</dd>
<dt>notes:</dt>
<dd>See <xref target="ChapterTimeEndNotes"/>.</dd>
</dl>
<t>notes:</t>
<table anchor="ChapterTimeEndNotes"><name>ChapterTimeEnd implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">minOccurs</td>
<td align="left">ChapterTimeEnd <bcp14>MUST</bcp14> be set (minOccurs=1) if the Edition <tt>Edition</tt> is an ordered edition; see <xref target="editionflagordered"></xref>, unless target="editionflagordered"/>. If it's a <tt>Parent Chapter</tt>; Chapter</tt>, see <xref target="nested-chapters"></xref></td> target="nested-chapters"/>.</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="chapterflaghidden-element"><name>ChapterFlagHidden Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x98 / uinteger / 0</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterFlagHidden</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Set to 1 if a chapter is hidden.
Hidden chapters <bcp14>SHOULD NOT</bcp14> be available to the user interface
(but still be available to Control Tracks; see <xref target="chapterflaghidden"></xref> target="chapterflaghidden"/> on Chapter <tt>Chapter</tt> flags).</dd>
</dl>
</section>

<section anchor="chaptersegmentuuid-element"><name>ChapterSegmentUUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6E67 / binary</dd>
<dt>length:</dt>
<dd>16</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterSegmentUUID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>see implementation notes
<dd>See <xref target="ChapterSegmentUUIDNotes"/> / 1</dd>
<dt>definition:</dt>
<dd>The SegmentUUID <tt>SegmentUUID</tt> of another Segment <tt>Segment</tt> to play during this chapter.</dd>
<dt>usage notes:</dt>
<dd>The value <bcp14>MUST NOT</bcp14> be the <tt>SegmentUUID</tt> value of the <tt>Segment</tt> it belongs to.</dd>
<dt>notes:</dt>
<dd>See <xref target="ChapterSegmentUUIDNotes"/>.</dd>
</dl>
<t>notes:</t>
<table anchor="ChapterSegmentUUIDNotes"><name>ChapterSegmentUUID implementation notes</name> Implementation Notes</name>
<thead>
<tr>
<th align="left">attribute</th>
<th align="left">note</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">minOccurs</td>
<td align="left">ChapterSegmentUUID align="left"><tt>ChapterSegmentUUID</tt> <bcp14>MUST</bcp14> be set (minOccurs=1) if ChapterSegmentEditionUID <tt>ChapterSegmentEditionUID</tt> is used; see <xref target="medium-linking"></xref> target="medium-linking"/> on medium-linking Segments.</td> Medium-Linking <tt>Segments</tt>.</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="chaptersegmenteditionuid-element"><name>ChapterSegmentEditionUID Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6EBC / uinteger</dd>
<dt>range:</dt>
<dd>not 0</dd> 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterSegmentEditionUID</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>The EditionUID <tt>EditionUID</tt> to play from the Segment <tt>Segment</tt> linked in ChapterSegmentUUID. <tt>ChapterSegmentUUID</tt>.
If ChapterSegmentEditionUID <tt>ChapterSegmentEditionUID</tt> is undeclared, then no Edition <tt>Edition</tt> of the linked Segment <tt>Linked Segment</tt> is used; see <xref target="medium-linking"></xref> target="medium-linking"/> on medium-linking Segments.</dd> Medium-Linking <tt>Segments</tt>.</dd>

</dl>
</section>

<section anchor="chapterphysicalequiv-element"><name>ChapterPhysicalEquiv Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x63C3 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterPhysicalEquiv</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Specify
<dd>Specifies the physical equivalent of this ChapterAtom like &quot;DVD&quot; <tt>ChapterAtom</tt>, e.g., "DVD" (60) or &quot;SIDE&quot; "SIDE" (50);
see <xref target="physical-types"></xref> target="physical-types"/> for a complete list of values.</dd>
</dl>
</section>

<section anchor="chapterdisplay-element"><name>ChapterDisplay Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x80 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay</tt></dd>
<dt>definition:</dt>
<dd>Contains all possible strings to use for the chapter display.</dd>
</dl>
</section>

<section anchor="chapstring-element"><name>ChapString Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x85 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\ChapString</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Contains the string to use as the chapter atom.</dd>
</dl>
</section>

<section anchor="chaplanguage-element"><name>ChapLanguage Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x437C / string / eng</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\ChapLanguage</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A language corresponding to the string,
in the Matroska languages form; see <xref target="language-codes"></xref> target="language-codes"/> on language codes.
This Element element <bcp14>MUST</bcp14> be ignored if a ChapLanguageBCP47 Element <tt>ChapLanguageBCP47</tt> element is used within the same ChapterDisplay Element.</dd> <tt>ChapterDisplay</tt> element.</dd>
</dl>
</section>

<section anchor="chaplanguagebcp47-element"><name>ChapLanguageBCP47 Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x437D / string</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\ChapLanguageBCP47</tt></dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>A language corresponding to the ChapString, <tt>ChapString</tt>,
in the form defined in <xref target="BCP47"></xref> form; target="RFC5646"/>; see <xref target="language-codes"></xref> target="language-codes"/> on language codes.
If a ChapLanguageBCP47 Element <tt>ChapLanguageBCP47</tt> element is used, then any ChapLanguage <tt>ChapLanguage</tt> and ChapCountry Elements <tt>ChapCountry</tt> elements used in the same ChapterDisplay <tt>ChapterDisplay</tt> <bcp14>MUST</bcp14> be ignored.</dd>
</dl>
</section>

<section anchor="chapcountry-element"><name>ChapCountry Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x437E / string</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\ChapCountry</tt></dd>
<dt>definition:</dt>
<dd>A country corresponding to the string,
in the Matroska countries form; see <xref target="country-codes"></xref> target="country-codes"/> on country codes.
This Element element <bcp14>MUST</bcp14> be ignored if a ChapLanguageBCP47 Element <tt>ChapLanguageBCP47</tt> element is used within the same ChapterDisplay Element.</dd> <tt>ChapterDisplay</tt> element.</dd>
</dl>
</section>

<section anchor="chapprocess-element"><name>ChapProcess Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6944 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess</tt></dd>
<dt>definition:</dt>
<dd>Contains all the commands associated to with the Atom.</dd>
</dl>
</section>

<section anchor="chapprocesscodecid-element"><name>ChapProcessCodecID Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x6955 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapProcessCodecID</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Contains the type of the codec used for the processing.
A value of 0 means built-in Matroska processing (to be defined), a value of 1 means the DVD command set is used; see processing.</dd>
<dt>defined values:</dt>
<dd>See <xref target="menu-features"></xref> on DVD menus.
More codec IDs target="ChapProcessCodecIDValues"/>. Additional values can be added later.</dd> registered in the "Matroska Chapter Codec IDs" registry defined in <xref target="matroska-chapter-codec-ids-registry"/>.</dd>
</dl>
<table anchor="ChapProcessCodecIDValues"><name>ChapProcessCodecID Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">Matroska Script</td>
<td align="left">Chapter commands using the Matroska Script codec.</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">DVD-menu</td>
<td align="left">Chapter commands using the DVD-like codec.</td>
</tr>
</tbody>
</table>
</section>

<section anchor="chapprocessprivate-element"><name>ChapProcessPrivate Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x450D / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapProcessPrivate</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>Some optional
<dd>Optional data attached to the ChapProcessCodecID <tt>ChapProcessCodecID</tt> information.
For ChapProcessCodecID <tt>ChapProcessCodecID</tt> = 1, it is the &quot;DVD level&quot; "DVD level" equivalent; see <xref target="menu-features"></xref> target="menu-features"/> on DVD menus.</dd>
</dl>
</section>

<section anchor="chapprocesscommand-element"><name>ChapProcessCommand Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6911 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapProcessCommand</tt></dd>
<dt>definition:</dt>
<dd>Contains all the commands associated to with the Atom.</dd>
</dl>
</section>

<section anchor="chapprocesstime-element"><name>ChapProcessTime Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6922 / uinteger</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapProcessCommand\ChapProcessTime</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Defines when the process command <bcp14>SHOULD</bcp14> be handled</dd> handled.</dd>
<dt>restrictions:</dt>
<dd>See <xref target="ChapProcessTimeValues"/>.</dd>
</dl>
<t>restrictions:</t>
<table anchor="ChapProcessTimeValues"><name>ChapProcessTime values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>0</tt></td>
<td align="left">during the whole chapter</td>
</tr>

<tr>
<td align="left"><tt>1</tt></td>
<td align="left">before starting playback</td>
</tr>

<tr>
<td align="left"><tt>2</tt></td>
<td align="left">after playback of the chapter</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="chapprocessdata-element"><name>ChapProcessData Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x6933 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapProcessCommand\ChapProcessData</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Contains the command information.
The data <bcp14>SHOULD</bcp14> be interpreted depending on the ChapProcessCodecID <tt>ChapProcessCodecID</tt> value. For ChapProcessCodecID <tt>ChapProcessCodecID</tt> = 1,
the data correspond to the binary DVD cell pre/post commands; see <xref target="menu-features"></xref> target="menu-features"/> on DVD menus.</dd>
</dl>
</section>
</section>
</section>
</section>

<section anchor="tags-element"><name>Tags Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x1254C367 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags</tt></dd>
<dt>definition:</dt>
<dd>Element containing metadata describing Tracks, Editions, Chapters, Attachments, <tt>Tracks</tt>, <tt>Editions</tt>, <tt>Chapters</tt>, <tt>Attachments</tt>, or the Segment <tt>Segment</tt> as a whole.
A list of valid tags can be found in <xref target="MatroskaTags"></xref>.</dd> target="I-D.ietf-cellar-tags"/>.</dd>
</dl>

<section anchor="tag-element"><name>Tag Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x7373 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>A single metadata descriptor.</dd>
</dl>

<section anchor="targets-element"><name>Targets Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x63C0 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\Targets</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Specifies which other elements the metadata represented by the Tag tag value applies to.
If empty or omitted, then the Tag tag value describes everything in the Segment.</dd> <tt>Segment</tt>.</dd>
</dl>

<section anchor="targettypevalue-element"><name>TargetTypeValue Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x68CA / uinteger / 50</dd>
<dt>range:</dt>
<dd>not 0 (1-18446744073709551615)</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\Targets\TargetTypeValue</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>A number to indicate the logical level of the target.</dd>
<dt>defined values:</dt>
<dd>See <xref target="TargetTypeValueValues"/>. Additional values can be registered in the "Matroska Tags Target Types" registry defined in <xref target="matroska-tags-target-types-registry"/>.</dd>
<dt>usage notes:</dt>
<dd>The <tt>TargetTypeValue</tt> values are meant to be compared.
Higher values <bcp14>MUST</bcp14> correspond to a logical level that contains the lower logical level <tt>TargetTypeValue</tt> values.</dd>
</dl>
<t>defined values:</t>
<table anchor="TargetTypeValueValues"><name>TargetTypeValue values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
<th align="left">definition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>70</tt></td>
<td align="left">COLLECTION</td>
<td align="left">The highest hierarchical level that tags can describe.</td>
</tr>

<tr>
<td align="left"><tt>60</tt></td>
<td align="left">EDITION / ISSUE / VOLUME / OPUS / SEASON / SEQUEL</td>
<td align="left">A list of lower levels grouped together.</td>
</tr>

<tr>
<td align="left"><tt>50</tt></td>
<td align="left">ALBUM / OPERA / CONCERT / MOVIE / EPISODE</td>
<td align="left">The most common grouping level of music and video (equals to (e.g., an episode for TV series).</td>
</tr>

<tr>
<td align="left"><tt>40</tt></td>
<td align="left">PART / SESSION</td>
<td align="left">When an album or episode has different logical parts.</td>
</tr>

<tr>
<td align="left"><tt>30</tt></td>
<td align="left">TRACK / SONG / CHAPTER</td>
<td align="left">The common parts of an album or movie.</td>
</tr>

<tr>
<td align="left"><tt>20</tt></td>
<td align="left">SUBTRACK / MOVEMENT / SCENE</td>
<td align="left">Corresponds to parts of a track for audio like audio, such as a movement, movement or a scene in a movie.</td>
</tr>

<tr>
<td align="left"><tt>10</tt></td>
<td align="left">SHOT</td>
<td align="left">The lowest hierarchy found in music or movies.</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="targettype-element"><name>TargetType Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x63CA / string</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\Targets\TargetType</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>An informational string that can be used to display the logical level of the target like &quot;ALBUM&quot;, &quot;TRACK&quot;, &quot;MOVIE&quot;, &quot;CHAPTER&quot;, target, such as "ALBUM", "TRACK", "MOVIE", "CHAPTER", etc.</dd>
<dt>restrictions:</dt>
<dd>See <xref target="TargetTypeValues"/>.</dd>
</dl>
<t>restrictions:</t>
<table anchor="TargetTypeValues"><name>TargetType values</name> Values</name>
<thead>
<tr>
<th align="left">value</th>
<th align="left">label</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>COLLECTION</tt></td>
<td align="left">TargetTypeValue 70</td>
</tr>

<tr>
<td align="left"><tt>EDITION</tt></td>
<td align="left">TargetTypeValue 60</td>
</tr>

<tr>
<td align="left"><tt>ISSUE</tt></td>
<td align="left">TargetTypeValue 60</td>
</tr>

<tr>
<td align="left"><tt>VOLUME</tt></td>
<td align="left">TargetTypeValue 60</td>
</tr>

<tr>
<td align="left"><tt>OPUS</tt></td>
<td align="left">TargetTypeValue 60</td>
</tr>

<tr>
<td align="left"><tt>SEASON</tt></td>
<td align="left">TargetTypeValue 60</td>
</tr>

<tr>
<td align="left"><tt>SEQUEL</tt></td>
<td align="left">TargetTypeValue 60</td>
</tr>

<tr>
<td align="left"><tt>ALBUM</tt></td>
<td align="left">TargetTypeValue 50</td>
</tr>

<tr>
<td align="left"><tt>OPERA</tt></td>
<td align="left">TargetTypeValue 50</td>
</tr>

<tr>
<td align="left"><tt>CONCERT</tt></td>
<td align="left">TargetTypeValue 50</td>
</tr>

<tr>
<td align="left"><tt>MOVIE</tt></td>
<td align="left">TargetTypeValue 50</td>
</tr>

<tr>
<td align="left"><tt>EPISODE</tt></td>
<td align="left">TargetTypeValue 50</td>
</tr>

<tr>
<td align="left"><tt>PART</tt></td>
<td align="left">TargetTypeValue 40</td>
</tr>

<tr>
<td align="left"><tt>SESSION</tt></td>
<td align="left">TargetTypeValue 40</td>
</tr>

<tr>
<td align="left"><tt>TRACK</tt></td>
<td align="left">TargetTypeValue 30</td>
</tr>

<tr>
<td align="left"><tt>SONG</tt></td>
<td align="left">TargetTypeValue 30</td>
</tr>

<tr>
<td align="left"><tt>CHAPTER</tt></td>
<td align="left">TargetTypeValue 30</td>
</tr>

<tr>
<td align="left"><tt>SUBTRACK</tt></td>
<td align="left">TargetTypeValue 20</td>
</tr>

<tr>
<td align="left"><tt>MOVEMENT</tt></td>
<td align="left">TargetTypeValue 20</td>
</tr>

<tr>
<td align="left"><tt>SCENE</tt></td>
<td align="left">TargetTypeValue 20</td>
</tr>

<tr>
<td align="left"><tt>SHOT</tt></td>
<td align="left">TargetTypeValue 10</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="tagtrackuid-element"><name>TagTrackUID Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x63C5 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\Targets\TagTrackUID</tt></dd>
<dt>definition:</dt>
<dd>A unique ID to identify UID that identifies the Track(s) <tt>Track(s)</tt> that the tags belong to.</dd>
<dt>usage notes:</dt>
<dd>If the value is 0 at this level, the tags apply to all tracks in the Segment. <tt>Segment</tt>.
If set to any other value, it <bcp14>MUST</bcp14> match the <tt>TrackUID</tt> value of a track found in this Segment.</dd> <tt>Segment</tt>.</dd>
</dl>
</section>

<section anchor="tageditionuid-element"><name>TagEditionUID Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x63C9 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\Targets\TagEditionUID</tt></dd>
<dt>definition:</dt>
<dd>A unique ID to identify UID that identifies the EditionEntry(s) <tt>EditionEntry(s)</tt> that the tags belong to.</dd>
<dt>usage notes:</dt>
<dd>If the value is 0 at this level, the tags apply to all editions in the Segment. <tt>Segment</tt>.
If set to any other value, it <bcp14>MUST</bcp14> match the <tt>EditionUID</tt> value of an edition found in this Segment.</dd> <tt>Segment</tt>.</dd>
</dl>
</section>

<section anchor="tagchapteruid-element"><name>TagChapterUID Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x63C4 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\Targets\TagChapterUID</tt></dd>
<dt>definition:</dt>
<dd>A unique ID to identify UID that identifies the Chapter(s) <tt>Chapter(s)</tt> that the tags belong to.</dd>
<dt>usage notes:</dt>
<dd>If the value is 0 at this level, the tags apply to all chapters in the Segment. <tt>Segment</tt>.
If set to any other value, it <bcp14>MUST</bcp14> match the <tt>ChapterUID</tt> value of a chapter found in this Segment.</dd> <tt>Segment</tt>.</dd>
</dl>
</section>

<section anchor="tagattachmentuid-element"><name>TagAttachmentUID Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x63C6 / uinteger / 0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\Targets\TagAttachmentUID</tt></dd>
<dt>definition:</dt>
<dd>A unique ID to identify UID that identifies the Attachment(s) that the tags belong to.</dd>
<dt>usage notes:</dt>
<dd>If the value is 0 at this level, the tags apply to all the attachments in
the Segment. <tt>Segment</tt>.  If set to any other value, it <bcp14>MUST</bcp14> match
the <tt>FileUID</tt> value of an attachment found in this Segment.</dd> <tt>Segment</tt>.</dd>
</dl>
</section>
</section>

<section anchor="simpletag-element"><name>SimpleTag Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x67C8 / master</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\+SimpleTag</tt></dd>
<dt>minOccurs:</dt>
<dd>1</dd>
</dl>
<t>recursive: True</t>

<dl spacing="compact">
<dt>recursive:</dt>
<dd>True</dd>
<dt>definition:</dt>
<dd>Contains general information about the target.</dd>
</dl>

<section anchor="tagname-element"><name>TagName Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x45A3 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\+SimpleTag\TagName</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>The name of the Tag tag value that is going to be stored.</dd>
</dl>
</section>

<section anchor="taglanguage-element"><name>TagLanguage Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x447A / string / und</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\+SimpleTag\TagLanguage</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>Specifies the language of the specified tag specified, in the Matroska languages form; see <xref target="language-codes"></xref> target="language-codes"/> on language codes.
This Element element <bcp14>MUST</bcp14> be ignored if the TagLanguageBCP47 Element <tt>TagLanguageBCP47</tt> element is used within the same SimpleTag Element.</dd> <tt>SimpleTag</tt> element.</dd>
</dl>
</section>

<section anchor="taglanguagebcp47-element"><name>TagLanguageBCP47 Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x447B / string</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\+SimpleTag\TagLanguageBCP47</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>minver:</dt>
<dd>4</dd>
<dt>definition:</dt>
<dd>The language used in the TagString, <tt>TagString</tt>,
in the form defined in <xref target="BCP47"></xref> form; target="RFC5646"/>; see <xref target="language-codes"></xref> target="language-codes"/> on language codes.
If this Element element is used, then any TagLanguage Elements <tt>TagLanguage</tt> elements used in the same SimpleTag <tt>SimpleTag</tt> <bcp14>MUST</bcp14> be ignored.</dd>
</dl>
</section>

<section anchor="tagdefault-element"><name>TagDefault Element</name>

<dl spacing="compact">
<dt>id / type / default:</dt>
<dd>0x4484 / uinteger / 1</dd>
<dt>range:</dt>
<dd>0-1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\+SimpleTag\TagDefault</tt></dd>
<dt>minOccurs / maxOccurs:</dt>
<dd>1 / 1</dd>
<dt>definition:</dt>
<dd>A boolean value to indicate if this is the default/original language to use for the given tag.</dd>
</dl>
</section>

<section anchor="tagstring-element"><name>TagString Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4487 / utf-8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\+SimpleTag\TagString</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>The value of the Tag.</dd> tag value.</dd>
</dl>
</section>

<section anchor="tagbinary-element"><name>TagBinary Element</name>

<dl spacing="compact">
<dt>id / type:</dt>
<dd>0x4485 / binary</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\+SimpleTag\TagBinary</tt></dd>
<dt>maxOccurs:</dt>
<dd>1</dd>
<dt>definition:</dt>
<dd>The values of the Tag, tag value if it is binary. Note that this cannot be used in the same SimpleTag <tt>SimpleTag</tt> as TagString.</dd> <tt>TagString</tt>.</dd>
</dl>
</section>
</section>
</section>
</section>
</section>
</section>

<section anchor="matroska-element-ordering"><name>Matroska Element Ordering</name>
<t>Except for
<t>With the exceptions of the <tt>EBML Header</tt> and the <tt>CRC-32 Element</tt>, <tt>CRC-32</tt>
element, the EBML specification <xref target="RFC8794"/> does not require any
particular storage order for <tt>Elements</tt>. This elements. However, this specification however defines
mandates and recommendations for ordering certain <tt>Elements</tt> in order elements to facilitate
better playback, seeking, and editing efficiency. This section describes and
offers rationale for ordering requirements and recommendations for
Matroska.</t>

<section anchor="top-level-elements"><name>Top-Level Elements</name>
<t>The <tt>Info Element</tt> <tt>Info</tt> element is the only <bcp14>REQUIRED</bcp14> <tt>Top-Level Element</tt> in a Matroska file.
To be playable, Matroska <bcp14>MUST</bcp14> also contain at least one <tt>Tracks Element</tt> <tt>Tracks</tt> element and <tt>Cluster Element</tt>. <tt>Cluster</tt> element.
The first <tt>Info Element</tt> <tt>Info</tt> element and the first <tt>Tracks Element</tt> <bcp14>MUST</bcp14> <tt>Tracks</tt> element either <bcp14>MUST</bcp14> be stored before the first
<tt>Cluster Element</tt>
<tt>Cluster</tt> element or both <bcp14>SHALL</bcp14> both be referenced by a <tt>SeekHead Element</tt> <tt>SeekHead</tt> element occurring before the first <tt>Cluster Element</tt>.</t> <tt>Cluster</tt> element.</t>
<t>All <tt>Top-Level Elements</tt> <bcp14>MUST</bcp14> use a 4-octet long EBML Element ID.</t>
<t>When using Medium Linking, chapters are used to reference other Segments <tt>Segments</tt> to play in a given order (see <xref target="medium-linking"></xref>. target="medium-linking"/>).
A Segment <tt>Segment</tt> containing these linked Chapters <tt>Linked Chapters</tt> does not require a <tt>Track</tt> Element <tt>Tracks</tt> element or a <tt>Cluster</tt> Element.</t> element.</t>
<t>It is possible to edit a Matroska file after it has been created. For
example, chapters, tags, or attachments can be added. When new <tt>Top-Level
Elements</tt> are added to a Matroska file, the <tt>SeekHead</tt> Element(s) element(s)
<bcp14>MUST</bcp14> be updated so that the <tt>SeekHead</tt> Element(s) itemize element(s)
itemizes the identity and position of all <tt>Top-Level Elements</tt>.</t>
<t>Editing, removing, or adding
<tt>Elements</tt> elements to a Matroska file often requires
that some existing <tt>Elements</tt> elements be voided or extended.  Transforming the existing <tt>Elements</tt>
elements into <tt>Void Elements</tt> <tt>Void</tt> elements as padding can be used as a method to
avoid moving large amounts of data around.</t>
</section>

<section anchor="crc-32"><name>CRC-32</name>
<t>As noted by the EBML specification, specification <xref target="RFC8794"/>, if a <tt>CRC-32 Element</tt> <tt>CRC-32</tt> element is used, then the <tt>CRC-32 Element</tt> <tt>CRC-32</tt> element
<bcp14>MUST</bcp14> be the first ordered <tt>Element</tt> element within its <tt>Parent Element</tt>.</t>
<t>In Matroska Matroska, all <tt>Top-Level Elements</tt> of an EBML Document <bcp14>SHOULD</bcp14> include a <tt>CRC-32 Element</tt> <tt>CRC-32</tt> element
as their first <tt>Child Element</tt>.
The <tt>Segment Element</tt>, <tt>Segment</tt> element, which is the <tt>Root Element</tt>, <bcp14>SHOULD NOT</bcp14> have a <tt>CRC-32 Element</tt>.</t> <tt>CRC-32</tt> element.</t>
</section>

<section anchor="seekhead"><name>SeekHead</name>
<t>If used, the first <tt>SeekHead Element</tt> <tt>SeekHead</tt> element <bcp14>MUST</bcp14> be the first non-<tt>CRC-32 Child Element</tt> Child</tt> element
of the <tt>Segment Element</tt>. <tt>Segment</tt> element. If a second <tt>SeekHead Element</tt> <tt>SeekHead</tt> element is used, then the first
<tt>SeekHead Element</tt>
<tt>SeekHead</tt> element <bcp14>MUST</bcp14> reference the identity and position of the second <tt>SeekHead</tt>.</t> <tt>SeekHead</tt> element.</t>
<t>Additionally, the second <tt>SeekHead Element</tt> <tt>SeekHead</tt> element <bcp14>MUST</bcp14> only reference <tt>Cluster</tt> Elements elements
and not any other <tt>Top-Level Element</tt> already contained within the first <tt>SeekHead Element</tt>.</t> <tt>SeekHead</tt> element.</t>
<t>The second <tt>SeekHead Element</tt> <tt>SeekHead</tt> element <bcp14>MAY</bcp14> be stored in any order relative to the other <tt>Top-Level Elements</tt>.
Whether one or two <tt>SeekHead Element(s)</tt> <tt>SeekHead</tt> elements are used, the <tt>SeekHead Element(s)</tt> <tt>SeekHead</tt> element(s) <bcp14>MUST</bcp14>
collectively reference the identity and position of all <tt>Top-Level Elements</tt> except
for the first <tt>SeekHead Element</tt>.</t> <tt>SeekHead</tt> element.</t>
</section>

<section anchor="cues-index"><name>Cues (index)</name> (Index)</name>
<t>The <tt>Cues Element</tt> <tt>Cues</tt> element is <bcp14>RECOMMENDED</bcp14> to optimize seeking access in Matroska. It is
programmatically simpler to add the <tt>Cues Element</tt> <tt>Cues</tt> element after all <tt>Cluster Elements</tt> <tt>Cluster</tt> elements
have been written because this does not require a prediction of how much space to
reserve before writing the <tt>Cluster Elements</tt>. <tt>Cluster</tt> elements. However, storing the <tt>Cues Element</tt> <tt>Cues</tt> element
before the <tt>Cluster Elements</tt> <tt>Cluster</tt> elements can provide some seeking advantages. If the <tt>Cues Element</tt> <tt>Cues</tt> element
is present, then it <bcp14>SHOULD</bcp14> either be stored before the first <tt>Cluster Element</tt> <tt>Cluster</tt> element
or be referenced by a <tt>SeekHead Element</tt>.</t> <tt>SeekHead</tt> element.</t>
</section>

<section anchor="info"><name>Info</name>
<t>The first <tt>Info Element</tt> <tt>Info</tt> element <bcp14>SHOULD</bcp14> occur before the first <tt>Tracks Element</tt> <tt>Tracks</tt> element and first
<tt>Cluster Element</tt>
<tt>Cluster</tt> element except when referenced by a <tt>SeekHead Element</tt>.</t> <tt>SeekHead</tt> element.</t>
</section>

<section anchor="chapters-element-1"><name>Chapters Element</name>
<t>The <tt>Chapters Element</tt> <tt>Chapters</tt> element <bcp14>SHOULD</bcp14> be placed before the <tt>Cluster Element(s)</tt>. <tt>Cluster</tt> element(s). The
<tt>Chapters Element</tt>
<tt>Chapters</tt> element can be used during playback even if the user does not need to seek.
It immediately gives the user information about what section is being read and what
other sections are available. In available.</t>
<t>In the case of Ordered Chapters <tt>Ordered Chapters</tt>, it is <bcp14>RECOMMENDED</bcp14> to evaluate
the logical linking even before playing. The <tt>Chapters Element</tt> <tt>Chapters</tt> element <bcp14>SHOULD</bcp14> be placed before
the first <tt>Tracks Element</tt> <tt>Tracks</tt> element and after the first <tt>Info Element</tt>.</t> <tt>Info</tt> element.</t>
</section>

<section anchor="attachments"><name>Attachments</name>
<t>The <tt>Attachments Element</tt> <tt>Attachments</tt> element is not intended to be used by default when playing the file, file
but could contain information relevant to the content, such as cover art or fonts.
Cover art is useful even before the file is played played, and fonts could be needed before playback
starts for the initialization of subtitles. The <tt>Attachments Element</tt> <tt>Attachments</tt> element <bcp14>MAY</bcp14> be placed before
the first <tt>Cluster Element</tt>; <tt>Cluster</tt> element; however, if the <tt>Attachments Element</tt> <tt>Attachments</tt> element is likely to be edited,
then it <bcp14>SHOULD</bcp14> be placed after the last <tt>Cluster Element</tt>.</t> <tt>Cluster</tt> element.</t>
</section>

<section anchor="tags"><name>Tags</name>
<t>The <tt>Tags Element</tt> <tt>Tags</tt> element is most subject to changes after the file was originally created.
For easier editing, the <tt>Tags Element</tt> <tt>Tags</tt> element can be placed at the end of the <tt>Segment Element</tt>, <tt>Segment</tt> element,
even after the <tt>Attachments Element</tt>. <tt>Attachments</tt> element. On the other hand, it is inconvenient to have to
seek in the <tt>Segment</tt> for tags, especially for network streams. So streams; thus, it's better if the
<tt>Tags Element</tt>
<tt>Tags</tt> element is found early in the stream. When editing the <tt>Tags Element</tt>, <tt>Tags</tt> element, the original
<tt>Tags Element</tt>
<tt>Tags</tt> element at the beginning can be overwritten with a <tt>Void Element</tt> <tt>Void</tt> element and a
new <tt>Tags Element</tt> <tt>Tags</tt> element written at the end of the <tt>Segment Element</tt>. <tt>Segment</tt> element. The file and Segment <tt>Segment</tt> sizes will only marginally change.</t>
</section>
</section>

<section anchor="matroska-versioning"><name>Matroska versioning</name> Versioning</name>
<t>Matroska is based upon on the principle that a reading application does not have to support
100% of the specifications in order to be able to play the file. A Therefore, a Matroska file therefore contains version indicators that tell a reading application what to expect.</t>
<t>It is possible and valid to have the version fields indicate that the file
contains Matroska <tt>Elements</tt> elements from a higher specification version number while
signaling that a reading application <bcp14>MUST</bcp14> only support a lower
version number properly in order to play it back (possibly with a reduced
feature set).</t>
<t>The <tt>EBML Header</tt> of each Matroska document informs the reading
application on what version of Matroska to expect. The <tt>Elements</tt> elements within the
<tt>EBML Header</tt> with jurisdiction over this information are
<tt>DocTypeVersion</tt> and <tt>DocTypeReadVersion</tt>.</t>
<t><tt>DocTypeVersion</tt> <bcp14>MUST</bcp14> be equal to or greater than the highest Matroska version number of
any <tt>Element</tt> element present in the Matroska file. For example, a file using the <tt>SimpleBlock Element</tt> <tt>SimpleBlock</tt> element (<xref target="simpleblock-element"></xref>) target="simpleblock-element"/>) <bcp14>MUST</bcp14> have a <tt>DocTypeVersion</tt> equal to or greater than 2. A file containing <tt>CueRelativePosition</tt>
Elements
elements  (<xref target="cuerelativeposition-element"></xref>) target="cuerelativeposition-element"/>) <bcp14>MUST</bcp14> have a <tt>DocTypeVersion</tt> equal to or greater than 4.</t>

<t>The <tt>DocTypeReadVersion</tt> <bcp14>MUST</bcp14> contain the minimum
version number that a reading application can minimally support in order to
play the file back -- optionally with a reduced feature set. For example, if a
file contains only <tt>Elements</tt> elements of version 2 or lower except for
<tt>CueRelativePosition</tt> (which is a version 4 Matroska <tt>Element</tt>), element), then
<tt>DocTypeReadVersion</tt> <bcp14>SHOULD</bcp14> still be set to 2 and not 4
because evaluating <tt>CueRelativePosition</tt> is not necessary for standard
playback -- it makes seeking more precise if used.</t>
<t>A reading application supporting Matroska version <tt>V</tt> <bcp14>MUST NOT</bcp14> refuse to read a
file with <tt>DocReadTypeVersion</tt> equal to or lower than <tt>V</tt> <tt>V</tt>, even if <tt>DocTypeVersion</tt>
is greater than <tt>V</tt>.</t>
<t>A reading application supporting at least Matroska version <tt>V</tt> and
reading a file whose <tt>DocTypeReadVersion</tt> field is equal to or lower
than <tt>V</tt> <bcp14>MUST</bcp14> skip Matroska/EBML <tt>Elements</tt> elements it encounters
but does not know about if that unknown element fits into the size constraints
set by the current <tt>Parent Element</tt>.</t>
</section>

<section anchor="stream-copy"><name>Stream Copy</name>
<t>It is sometimes necessary to create a Matroska file from another Matroska file, for example example, to add subtitles in a language
or to edit out a portion of the content.
Some values from the original Matroska file need to be kept the same in the destination file.
For example, the SamplingFrequency <tt>SamplingFrequency</tt> of an audio track wouldn't change between the two files.
Some other values may change between the two files, for example example, the TrackNumber <tt>TrackNumber</tt> of an audio track when another track has been added.</t>
<t>An Element element is marked with a property: <tt>stream property "<tt>stream copy: True</tt> True</tt>" when the values of that Element element need to be kept identical between the source and destination file. files.
If that property is not set, elements may or may not keep the same value between the source and destination.</t> destination files.</t>
</section>

<section anchor="defaultdecodedfieldduration"><name>DefaultDecodedFieldDuration</name>
<t>The <tt>DefaultDecodedFieldDuration Element</tt> <tt>DefaultDecodedFieldDuration</tt> element can signal to the
displaying application how often fields of a video sequence will be available
for displaying. It can be used for both interlaced and progressive
content.</t>
<t>If the video sequence is signaled as interlaced <xref target="flaginterlaced-element"></xref>, (<xref target="flaginterlaced-element"/>), then <tt>DefaultDecodedFieldDuration</tt> equals
the period between two successive fields at the output of the decoding process.
For video sequences signaled as progressive, <tt>DefaultDecodedFieldDuration</tt> is half of
the period between two successive frames at the output of the decoding process.</t>
<t>These values are valid at the end of the decoding process before post-processing
(such as deinterlacing or inverse telecine) is applied.</t>
<t>Examples:</t>

<ul spacing="compact">
<li>Blu-ray

<ul>
<li><t>Blu-ray movie:      1000000000 ns/(48/1.001) = 20854167 ns</li>
<li>PAL ns</t>
</li>
<li><t>PAL broadcast/DVD:  1000000000 ns/(50/1.000) = 20000000 ns</li>
<li>N/ATSC ns</t>
</li>
<li><t>N/ATSC broadcast:   1000000000 ns/(60/1.001) = 16683333 ns</li>
<li>hard-telecined ns</t>
</li>
<li><t>Hard-telecined DVD: 1000000000 ns/(60/1.001) = 16683333 ns (60 encoded interlaced fields per second)</li>
<li>soft-telecined second)</t>
</li>
<li><t>Soft-telecined DVD: 1000000000 ns/(60/1.001) = 16683333 ns (48 encoded interlaced fields per second, with &quot;repeat_first_field "repeat_first_field = 1&quot;)</li> 1")</t>
</li>
</ul>
</section>

<section anchor="cluster-blocks"><name>Cluster Blocks</name>
<t>Frames using references <bcp14>SHOULD</bcp14> be stored in &quot;coding order&quot;. That means "coding order" (i.e., the references first, first and then
the frames referencing them. them). A consequence is that timestamps might not be consecutive.
But
However, a frame with a past timestamp <bcp14>MUST</bcp14> reference a frame already known, otherwise it's known; otherwise, it is considered bad/void.</t>
<t>Matroska has two similar ways to store frames in a block:</t>

<ul spacing="compact">
<li>in

<ul>
<li><t>in a <tt>Block</tt> which that is contained inside a <tt>BlockGroup</tt>,</li>
<li>or in <tt>BlockGroup</tt></t>
</li>
<li><t>in a <tt>SimpleBlock</tt> which that is directly in the <tt>Cluster</tt>.</li> <tt>Cluster</tt></t>
</li>
</ul>
<t>The <tt>SimpleBlock</tt> is usually preferred unless some extra elements of the <tt>BlockGroup</tt> need to be used.
A Matroska Reader <tt>Matroska Reader</tt> <bcp14>MUST</bcp14> support both types of blocks.</t>
<t>Each block contains the same parts in the following order:</t>

<ul spacing="compact">
<li>a variable length header,</li>
<li>optionally the

<ul>
<li><t>a variable-length header</t>
</li>
<li><t>the lacing information,</li>
<li>the information (optional)</t>
</li>
<li><t>the consecutive frame(s)</li> frame(s)</t>
</li>
</ul>
<t>The block header starts with the number of the Track <tt>Track</tt> it corresponds to.
The value <bcp14>MUST</bcp14> corresponding correspond to the <tt>TrackNumber</tt> (<xref target="tracknumber-element"></xref>) target="tracknumber-element"/>) of a <tt>TrackEntry</tt> of the <tt>Segment</tt>.</t>
<t>The <tt>TrackNumber</tt> is coded using the VINT Variable-Size Integer (VINT) mechanism described in Section 4 of <xref target="RFC8794"></xref>. target="RFC8794" sectionFormat="of" section="4"/>.
To save space, the shortest VINT form <bcp14>SHOULD</bcp14> be used. The value can be coded on using up to 8 octets.
This is the only element with a variable size in the block header.</t>
<t>The timestamp is expressed in Track Ticks; see <xref target="timestamp-ticks"></xref>. target="timestamp-ticks"/>.
The value is stored as a signed value on 16 bits.</t>

<section anchor="block-structure"><name>Block Structure</name>
<t>This section describes the binary data contained in the <tt>Block</tt> Element <xref target="block-element"></xref>. element (<xref target="block-element"/>). Bit 0 is the most significant bit.</t>
<t>As the <tt>TrackNumber</tt> size can vary between 1 and 8 octets, there are 8 different sizes for the <tt>Block</tt> header.
We only provide the
The definitions for <tt>TrackNumber</tt> sizes of 1 and 2.
The 2 are provided; the other variants can be deduced by extending the size of the <tt>TrackNumber</tt> by multiples of 8 bits.</t>
<figure><name>Block Header with 1 octet 1-Octet TrackNumber
</name>
<artwork>
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |               |                               |       |I|LAC|U|
 |  Track Number |         Timestamp             | Rsvrd |N|ING|N|
 |               |                               |       |V|   |U|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

</artwork>
</figure>
<figure><name>Block Header with 2 octets 2-Octet TrackNumber
</name>
<artwork>
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |          Track Number         |         Timestamp             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |       |I|LAC|U|
 | Rsvrd |N|ING|N|                     ...
 |       |V|   |U|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

</artwork>
</figure>
<t>where:</t>

<dl newline="true" newline="false" spacing="normal">
<dt>Track Number: 8, Number:</dt>
<dd>8, 16, 24, 32, 40, 48 48, or 64 bits</dt>
<dd>an 56 bits. An EBML VINT coded VINT-coded track number</dd>
<dt>Timestamp: 16 bits</dt>
<dd>signed number.</dd>
<dt>Timestamp:</dt>
<dd>16 bits. Signed timestamp in Track Ticks</dd>
<dt>Rsvrd: 4 bits</dt>
<dd>Reserved Ticks.</dd>
<dt>Rsvrd:</dt>
<dd>4 bits. Reserved bits <bcp14>MUST</bcp14> be set to 0</dd>
<dt>INV: 1 bit</dt>
<dd>Invisible, the 0.</dd>
<dt>INV:</dt>
<dd>1 bit. Invisible; The codec <bcp14>SHOULD</bcp14> decode this frame but not display it</dd>
<dt>LACING: 2 bits</dt>
<dd><t>using it.</dd>
<dt>LACING:</dt>
<dd><t>2 bits. Uses lacing mode</t>

<ul mode.</t>

<dl spacing="compact">
<li>00b : no
<dt>00b:</dt>
<dd>no lacing (<xref target="no-lacing"></xref>)</li>
<li>01b : Xiph target="no-lacing"/>)</dd>
<dt>01b:</dt><dd>Xiph lacing (<xref target="xiph-lacing"></xref>)</li>
<li>11b : EBML target="xiph-lacing"/>)</dd>
<dt>11b:</dt><dd>EBML lacing (<xref target="ebml-lacing"></xref>)</li>
<li>10b : fixed-size target="ebml-lacing"/>)</dd>
<dt>10b:</dt><dd>fixed-size lacing (<xref target="fixed-size-lacing"></xref>)</li>
</ul></dd>
<dt>UNU: 1 bit</dt>
<dd>unused bit</dd> target="fixed-size-lacing"/>)</dd>
</dl></dd>
<dt>UNU:</dt>
<dd>1 bit. Unused bit.</dd>
</dl>
<t>The following remaining data in the <tt>Block</tt> correspond corresponds to the lacing data and frames usage as described in each respective lacing mode.</t> mode (see <xref target="block-lacing"/>).</t>
</section>

<section anchor="simpleblock-structure"><name>SimpleBlock Structure</name>
<t>This section describes the binary data contained in the <tt>SimpleBlock</tt> Element <xref target="simpleblock-element"></xref>. element (<xref target="simpleblock-element"/>). Bit 0 is the most significant bit.</t>

<t>The <tt>SimpleBlock</tt> structure is inspired by the Block <tt>Block</tt> structure; see <xref target="block-structure"></xref>. target="block-structure"/>.
The main differences are the added Keyframe flag and Discardable flag. Otherwise, everything is the same.</t>
<t>As the <tt>TrackNumber</tt> size can vary between 1 and 8 octets, there are 8 different sizes for the <tt>SimpleBlock</tt> header.
We only provide the
The definitions for <tt>TrackNumber</tt> sizes of 1 and 2.
The 2 are provided; the
other variants can be deduced by extending the size of the
<tt>TrackNumber</tt> by multiples of 8 bits.</t>
<figure><name>SimpleBlock Header with 1 octet 1-Octet TrackNumber
</name>
<artwork>
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |               |                               |K|     |I|LAC|D|
 |  Track Number |         Timestamp             |E|Rsvrd|N|ING|I|
 |               |                               |Y|     |V|   |S|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

</artwork>
</figure>
<figure><name>SimpleBlock Header with 2 octets 2-Octet TrackNumber
</name>
<artwork>
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |          Track Number         |         Timestamp             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |K|     |I|LAC|D|
 |E|Rsvrd|N|ING|I|                     ...
 |Y|     |V|   |S|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

</artwork>
</figure>
<t>where:</t>

<dl newline="true" newline="false" spacing="normal">
<dt>Track Number: 8, Number:</dt>
<dd>8, 16, 24, 32, 40, 48 48, or 64 bits</dt>
<dd>an 56 bits. An EBML VINT coded VINT-coded track number</dd>
<dt>Timestamp: 16 bits</dt>
<dd>signed number.</dd>
<dt>Timestamp:</dt>
<dd>16 bits. Signed timestamp in Track Ticks</dd>
<dt>KEY: 1 bit</dt>
<dd>Keyframe, set Ticks.</dd>
<dt>KEY:</dt>
<dd>1 bit. Keyframe; Set when the Block <tt>Block</tt> contains only keyframes</dd>
<dt>Rsvrd: 3 bits</dt>
<dd>Reserved keyframes.</dd>
<dt>Rsvrd:</dt>
<dd>3 bits. Reserved bits <bcp14>MUST</bcp14> be set to 0</dd>
<dt>INV: 1 bit</dt>
<dd>Invisible, 0.</dd>
<dt>INV:</dt>
<dd>1 bit. Invisible; the codec <bcp14>SHOULD</bcp14> decode this frame but not display it</dd>
<dt>LACING: 2 bits</dt>
<dd><t>using it.</dd>
<dt>LACING:</dt>
<dd><t>2 bits. Uses lacing mode</t>

<ul mode.</t>

<dl spacing="compact">
<li>00b : no
<dt>00b:</dt>
<dd>no lacing (<xref target="no-lacing"></xref>)</li>
<li>01b : Xiph target="no-lacing"/>)</dd>
<dt>01b:</dt><dd>Xiph lacing (<xref target="xiph-lacing"></xref>)</li>
<li>11b : EBML target="xiph-lacing"/>)</dd>
<dt>11b:</dt><dd>EBML lacing (<xref target="ebml-lacing"></xref>)</li>
<li>10b : fixed-size target="ebml-lacing"/>)</dd>
<dt>10b:</dt><dd>fixed-size lacing (<xref target="fixed-size-lacing"></xref>)</li>
</ul></dd>
<dt>DIS: 1 bit</dt>
<dd>Discardable, the target="fixed-size-lacing"/>)</dd>
</dl></dd>
<dt>DIS:</dt>
<dd>1 bit. Discardable; The frames of the Block <tt>Block</tt> can be discarded during playing if needed</dd> needed.</dd>
</dl>
<t>The following remaining data in the <tt>SimpleBlock</tt> correspond corresponds to the lacing data and frames usage as described in each respective lacing mode.</t> mode (see <xref target="block-lacing"/>).</t>
</section>

<section anchor="block-lacing"><name>Block Lacing</name>
<t>Lacing is a mechanism to save space when storing data. It is typically used for small blocks
of data (referred to as frames in Matroska). It packs multiple frames into a single <tt>Block</tt> or <tt>SimpleBlock</tt>.</t>
<t>Lacing <bcp14>MUST NOT</bcp14> be used to store a single frame in a <tt>Block</tt> or <tt>SimpleBlock</tt>.</t>
<t>There are 3 three types of lacing:</t>

<ol spacing="compact">
<li>Xiph,

<ul>
<li><t>Xiph, which is inspired by what is found in the Ogg container <xref target="RFC3533"></xref></li>
<li>EBML, target="RFC3533"/></t>
</li>
<li><t>EBML, which is the same with sizes coded differently</li>
<li>fixed-size, differently</t>
</li>
<li><t>Fixed-size, where the size is not coded</li>
</ol> coded</t>
</li>
</ul>
<t>When lacing is not used, i.e. i.e., to store a single frame, the lacing bits (bits 5 and 6 6) of the <tt>Block</tt> or <tt>SimpleBlock</tt> <bcp14>MUST</bcp14> be set to zero.</t>
<t>For example, a user wants to store 3 three frames of the same track. The first frame is 800 octets long,
the second is 500 octets long long, and the third is 1000 octets long. As
Because these data frames are small,
they can be stored in a lace to save space.</t>
<t>It is possible not to not use lacing at all and just store a single frame without any extra data.
When the FlagLacing -- <xref target="flaglacing-element"></xref> -- <tt>FlagLacing</tt> (<xref target="flaglacing-element"/>) is set to &quot;0&quot; 0, all blocks of that track <bcp14>MUST NOT</bcp14> use lacing.</t>

<section anchor="no-lacing"><name>No lacing</name> Lacing</name>
<t>When no lacing is used, the number of frames in the lace is ommitted omitted, and only one frame can be stored in the Block. <tt>Block</tt>. The LACING bits 5-6 of the Block <tt>Block</tt> Header flags are set to <tt>0b00</tt>.</t> <tt>00b</tt>.</t>
<t>The Block <tt>Block</tt> for an 800 octets 800-octet frame is as follows:</t>
<table anchor="blockNoLacing"><name>No lacing</name> Lacing</name>
<thead>
<tr>
<th align="left">Block Octets</th> Octet</th>
<th align="left">Value</th>
<th align="left">Description</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">4-803</td>
<td align="left">&lt;frame&gt;</td>
<td align="left">Single frame data</td>
</tr>
</tbody>
</table><t>When a Block <tt>Block</tt> contains a single frame, it <bcp14>MUST</bcp14> use this No lacing "no lacing" mode.</t>
</section>

<section anchor="xiph-lacing"><name>Xiph lacing</name> Lacing</name>
<t>The Xiph lacing uses the same coding of size as found in the Ogg container <xref target="RFC3533"></xref>. target="RFC3533"/>.
The LACING bits 5-6 of the Block <tt>Block</tt> Header flags are set to <tt>0b01</tt>.</t> <tt>01b</tt>.</t>
<t>The Block <tt>Block</tt> data with laced frames is stored as follows:</t>

<ul spacing="compact">
<li>Lacing

<ul>
<li><t>Lacing Head on 1 Octet: Number of frames in the lace minus 1.</li>
<li>Lacing 1.</t>
</li>
<li><t>Lacing size of each frame except the last one.</li>
<li>Binary one.</t>
</li>
<li><t>Binary data of each frame consecutively.</li> consecutively.</t>
</li>
</ul>
<t>The lacing size is split into 255 values, stored as unsigned octets -- for example, 500 is coded 255;245 or [0xFF 0xF5].
A frame with a size multiple of 255 is coded with a 0 at the end of the size -- for example, 765 is coded 255;255;255;0 or [0xFF 0xFF 0xFF 0x00].</t>
<t>The size of the last frame is deduced from the size remaining in the Block <tt>Block</tt> after the other frames.</t>
<t>Because large sizes result in large coding of the sizes, it is <bcp14>RECOMMENDED</bcp14> to use Xiph lacing only with small frames.</t>
<t>In our example, the 800, 500 800-, 500-, and 1000 1000-octet frames are stored with Xiph lacing in a Block <tt>Block</tt> as follows:</t>
<table anchor="blockXiphLacing"><name>Xiph lacing example</name> Lacing Example</name>
<thead>
<tr>
<th align="left">Block Octet</th> Octets</th>
<th align="left">Value</th>
<th align="left">Description</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">4</td>
<td align="left">0x02</td>
<td align="left">Number of frames minus 1</td>
</tr>

<tr>
<td align="left">5-8</td>
<td align="left">0xFF 0xFF 0xFF 0x23</td>
<td align="left">Size of the first frame (255;255;255;35)</td>
</tr>

<tr>
<td align="left">9-10</td>
<td align="left">0xFF 0xF5</td>
<td align="left">Size of the second frame (255;245)</td>
</tr>

<tr>
<td align="left">11-810</td>
<td align="left"></td>
<td align="left">First frame data</td>
</tr>

<tr>
<td align="left">811-1310</td>
<td align="left"></td>
<td align="left">Second frame data</td>
</tr>

<tr>
<td align="left">1311-2310</td>
<td align="left"></td>
<td align="left">Third frame data</td>
</tr>
</tbody>
</table><t>The Block <tt>Block</tt> is 2311 octets large octets, and the last frame starts at 1311, so we can deduce that the size of the last frame is 2311 - 1311 = 1000.</t>
</section>

<section anchor="ebml-lacing"><name>EBML lacing</name> Lacing</name>
<t>The EBML lacing encodes the frame size with an EBML-like encoding <xref target="RFC8794"></xref>. target="RFC8794"/>.
The LACING bits 5-6 of the Block <tt>Block</tt> Header flags are set to <tt>0b11</tt>.</t> <tt>11b</tt>.</t>
<t>The Block <tt>Block</tt> data with laced frames is stored as follows:</t>

<ul spacing="compact">
<li>Lacing

<ul>
<li><t>Lacing Head on 1 Octet: Number of frames in the lace minus 1.</li>
<li>Lacing 1.</t>
</li>
<li><t>Lacing size of each frame except the last one.</li>
<li>Binary one.</t>
</li>
<li><t>Binary data of each frame consecutively.</li> consecutively.</t>
</li>
</ul>
<t>The first frame size is encoded as an EBML Variable-Size Integer value, also known as VINT in <xref target="RFC8794"></xref>. value.
The remaining frame sizes are encoded as signed values using the difference between the frame size and the previous frame size.
These signed values are encoded as VINT, with a mapping from signed to unsigned numbers.
Decoding the unsigned number stored in the VINT to a signed number is done by subtracting 2<sup>((7*n)-1)</sup>-1, where <tt>n</tt> is the octet size of the VINT.</t>
<table anchor="ebmlLacingBits"><name>EBML Lacing signed Signed VINT bits usage</name> Bits Usage</name>
<thead>
<tr>
<th align="left">Bit Representation of signed Signed VINT</th>
<th align="left">Possible Value Range</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">1xxx xxxx</td>
<td align="left">2^7 values from -(2<sup>6</sup>-1) to 2<sup>6</sup></td>
</tr>

<tr>
<td align="left">01xx xxxx  xxxx xxxx</td>
<td align="left">2^14 values from -(2<sup>13</sup>-1) to 2<sup>13</sup></td>
</tr>

<tr>
<td align="left">001x xxxx  xxxx xxxx  xxxx xxxx</td>
<td align="left">2^21 values from -(2<sup>20</sup>-1) to 2<sup>20</sup></td>
</tr>

<tr>
<td align="left">0001 xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx</td>
<td align="left">2^28 values from -(2<sup>27</sup>-1) to 2<sup>27</sup></td>
</tr>

<tr>
<td align="left">0000 1xxx  xxxx xxxx  xxxx xxxx  xxxx xxxx  xxxx xxxx</td>
<td align="left">2^35 values from -(2<sup>34</sup>-1) to 2<sup>34</sup></td>
</tr>
</tbody>
</table><t>In our example, the 800, 500 800-, 500-, and 1000 1000-octet frames are stored with EBML lacing in a Block <tt>Block</tt> as follows:</t>
<table anchor="blockEbmlLacing"><name>EBML lacing example</name> Lacing Example</name>
<thead>
<tr>
<th align="left">Block Octets</th>
<th align="left">Value</th>
<th align="left">Description</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">4</td>
<td align="left">0x02</td>
<td align="left">Number of frames minus 1</td>
</tr>

<tr>
<td align="left">5-6</td>
<td align="left">0x43 0x20</td>
<td align="left">Size of the first frame (800 = 0x320 + 0x4000)</td>
</tr>

<tr>
<td align="left">7-8</td>
<td align="left">0x5E 0xD3</td>
<td align="left">Size of the second frame (500 - 800 = -300 = - 0x12C + 0x1FFF + 0x4000)</td>
</tr>

<tr>
<td align="left">8-807</td>
<td align="left">&lt;frame1&gt;</td>
<td align="left">First frame data</td>
</tr>

<tr>
<td align="left">808-1307</td>
<td align="left">&lt;frame2&gt;</td>
<td align="left">Second frame data</td>
</tr>

<tr>
<td align="left">1308-2307</td>
<td align="left">&lt;frame3&gt;</td>
<td align="left">Third frame data</td>
</tr>
</tbody>
</table><t>The Block <tt>Block</tt> is 2308 octets large octets, and the last frame starts at 1308, so we can deduce that the size of the last frame is 2308 - 1308 = 1000.</t>
</section>

<section anchor="fixed-size-lacing"><name>Fixed-size lacing</name>
<t>The Fixed-size Lacing</name>
<t>Fixed-size lacing doesn't store the frame size, size; rather, it only stores the number of frames in the lace.
Each frame <bcp14>MUST</bcp14> have the same size. The frame size of each frame is deduced from the total size of the Block. <tt>Block</tt>.
The LACING bits 5-6 of the Block <tt>Block</tt> Header flags are set to <tt>0b10</tt>.</t> <tt>10b</tt>.</t>
<t>The Block <tt>Block</tt> data with laced frames is stored as follows:</t>

<ul spacing="compact">
<li>Lacing

<ul>
<li><t>Lacing Head on 1 Octet: Number of frames in the lace minus 1.</li>
<li>Binary 1.</t>
</li>
<li><t>Binary data of each frame consecutively.</li> consecutively.</t>
</li>
</ul>
<t>For example, for 3 three frames of that are 800 octets each:</t>
<table anchor="blockFixedSizeLacing"><name>Fixed-size lacing example</name> anchor="blockFixedSizeLacing"><name>Fixed-Size Lacing Example</name>
<thead>
<tr>
<th align="left">Block Octets</th>
<th align="left">Value</th>
<th align="left">Description</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">4</td>
<td align="left">0x02</td>
<td align="left">Number of frames minus 1</td>
</tr>

<tr>
<td align="left">5-804</td>
<td align="left">&lt;frame1&gt;</td>
<td align="left">First frame data</td>
</tr>

<tr>
<td align="left">805-1604</td>
<td align="left">&lt;frame2&gt;</td>
<td align="left">Second frame data</td>
</tr>

<tr>
<td align="left">1605-2404</td>
<td align="left">&lt;frame3&gt;</td>
<td align="left">Third frame data</td>
</tr>
</tbody>
</table><t>This gives a Block <tt>Block</tt> of 2405 octets. When reading the Block <tt>Block</tt>, we find that there are 3 three frames (Octet 4). The data start at Octet 5, so the size of each frame is (2405 - 5) / 3 = 800.</t>
</section>

<section anchor="laced-frames-timestamp"><name>Laced Frames Timestamp</name>
<t>A Block <tt>Block</tt> only contains a single timestamp value. But when lacing is used, it contains more than one frame.
Each frame originally has its own timestamp, or Presentation Timestamp (PTS). That timestamp applies to
the first frame in the lace.</t>
<t>In the lace, each frame after the first one has an underdetermined timestamp.
But
However, each of these frames <bcp14>MUST</bcp14> be contiguous -- i.e. i.e., the decoded data <bcp14>MUST NOT</bcp14> contain any gap
between them. If there is a gap in the stream, the frames around the gap <bcp14>MUST NOT</bcp14> be in the same Block.</t> <tt>Block</tt>.</t>
<t>Lacing is only useful for small contiguous data to save space. This is usually the case for audio tracks
and not the case for video -- which (which use a lot of data -- data) or subtitle tracks -- which (which have long gaps. gaps).
For audio, there is usually a fixed output sampling frequency for the whole track.
So track,
so the decoder should be able to recover the timestamp of each sample, knowing each
output sample is contiguous with a fixed frequency.
For subtitles subtitles, this is usually not the case case, so lacing <bcp14>SHOULD NOT</bcp14> be used.</t>
</section>
</section>

<section anchor="random-access-points"><name>Random Access Points</name>
<t>Random Access Points (RAP) (RAPs) are positions where the parser can seek to and
start playback without decoding
of what was before. In Matroska Matroska,
<tt>BlockGroups</tt> and <tt>SimpleBlocks</tt> can be RAPs.  To seek to these elements
elements, it is still necessary to seek to the <tt>Cluster</tt> containing
them, read the Cluster Timestamp <tt>Cluster</tt> Timestamp, and start playback from the
<tt>BlockGroup</tt> or <tt>SimpleBlock</tt> that is a RAP.</t>
<t>Because a Matroska File is usually composed of multiple tracks playing at the same time
-- video, audio audio, and subtitles -- to seek properly to a RAP, each selected track must be
taken in into account. Usually Usually, all audio and subtitle <tt>BlockGroup</tt> <tt>BlockGroups</tt> or <tt>SimpleBlock</tt> <tt>SimpleBlocks</tt> are RAP. RAPs.
They are independent of each other and can be played randomly.</t>
<t>Video tracks on
<t>On the other hand hand, video tracks often use references to previous and future
frames for better coding efficiency. Frames with such reference references
<bcp14>MUST</bcp14> either contain one or more <tt>ReferenceBlock</tt> Elements
elements in their <tt>BlockGroup</tt> or <bcp14>MUST</bcp14> be marked as
non-keyframe in a <tt>SimpleBlock</tt>; see <xref target="simpleblock-structure"></xref>.</t>

<ul spacing="compact">
<li>BlockGroup
target="simpleblock-structure"/>.</t>
<figure><name>BlockGroup with a frame that references another frame, Frame That References Another Frame, with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;BlockGroup&gt;
    &lt;!-- References a Block 40 Track Ticks before this one --&gt;
    &lt;ReferenceBlock&gt;-40&lt;/ReferenceBlock&gt;
    &lt;Block/&gt;
  &lt;/BlockGroup&gt;
  ...
&lt;/Cluster&gt;

</sourcecode>

<ul spacing="compact">
<li>SimpleBlock
</figure>
<figure><name>SimpleBlock with a frame that references another frame, Frame That References Another Frame, with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;SimpleBlock/&gt; (octet 3 bit 0 not set)
  ...
&lt;/Cluster&gt;

</sourcecode>
</figure>
<t>Frames that are RAP -- i.e. they RAPs (i.e., frames that don't depend on other frames -- frames) <bcp14>MUST</bcp14> set the keyframe
flag if they are in a <tt>SimpleBlock</tt> or their parent <tt>BlockGroup</tt> <bcp14>MUST NOT</bcp14> contain
a <tt>ReferenceBlock</tt>.</t>

<ul spacing="compact">
<li>BlockGroup
<figure><name>BlockGroup with a frame that references no other frame, Frame That References No Other Frame, with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;BlockGroup&gt;
    &lt;!-- No ReferenceBlock allowed in this BlockGroup --&gt;
    &lt;Block/&gt;
  &lt;/BlockGroup&gt;
  ...
&lt;/Cluster&gt;

</sourcecode>

<ul spacing="compact">
<li>SimpleBlock
</figure>
<figure><name>SimpleBlock with a frame that references no other frame, Frame That References No Other Frame, with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;SimpleBlock/&gt; (octet 3 bit 0 set)
  ...
&lt;/Cluster&gt;

</sourcecode>
</figure>
<t>There may be cases where the use of <tt>BlockGroup</tt> is necessary, as the frame may need a
<tt>BlockDuration</tt>, <tt>BlockAdditions</tt>, <tt>CodecState</tt> <tt>CodecState</tt>, or a <tt>DiscardPadding</tt> element.
For thoses cases those cases, a <tt>SimpleBlock</tt> <bcp14>MUST NOT</bcp14> be used, used;
the reference information <bcp14>SHOULD</bcp14> be recovered for non-RAP frames.</t>

<ul spacing="compact">
<li>SimpleBlock
<figure><name>SimpleBlock with a frame that references another frame, Frame That References Another Frame, with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;SimpleBlock/&gt; (octet 3 bit 0 not set)
  ...
&lt;/Cluster&gt;

</sourcecode>

<ul spacing="compact">
<li>Same frame that references another frame put
</figure>
<figure><name>Same Frame That References Another Frame Put inside a BlockGroup <tt>BlockGroup</tt> to add Add <tt>BlockDuration</tt>, with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;BlockGroup&gt;
    &lt;!-- ReferenceBlock value recovered based on the codec --&gt;
    &lt;ReferenceBlock&gt;-40&lt;/ReferenceBlock&gt;
    &lt;BlockDuration&gt;20&lt;BlockDuration&gt;
    &lt;BlockDuration&gt;20&lt;/BlockDuration&gt;
    &lt;Block/&gt;
  &lt;/BlockGroup&gt;
  ...
&lt;/Cluster&gt;

</sourcecode>
</figure>
<t>When a frame in a <tt>BlockGroup</tt> is not a RAP, the <tt>BlockGroup</tt> <bcp14>MUST</bcp14> contain at least a <tt>ReferenceBlock</tt>.
The <tt>ReferenceBlock</tt>s <bcp14>MUST</bcp14> be used in one of the following ways:</t>

<ul spacing="compact">
<li>each

<ul>
<li><t>each reference frame listed as a <tt>ReferenceBlock</tt>,</li>
<li>some <tt>ReferenceBlock</tt>,</t>
</li>
<li><t>some referenced frame frames listed as a <tt>ReferenceBlock</tt>, even if the timestamp value is accurate,</li>
<li>or one accurate, or</t>
</li>
<li><t>one <tt>ReferenceBlock</tt> with the timestamp value &quot;0&quot; "0" corresponding to a self or unknown reference.</li> reference.</t>
</li>
</ul>
<t>The lack of <tt>ReferenceBlock</tt> would mean such a frame is a RAP RAP, and seeking on that
frame that actually depends on other frames may create a bogus output or even crash.</t>

<ul spacing="compact">
<li>Same frame that references another frame put
<figure><name>Same Frame That References Another Frame Put inside a BlockGroup <tt>BlockGroup</tt>, but the reference could not be recovered, Reference Could Not Be Recovered, with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;BlockGroup&gt;
    &lt;!-- ReferenceBlock value not recovered from the codec --&gt;
    &lt;ReferenceBlock&gt;0&lt;/ReferenceBlock&gt;
    &lt;BlockDuration&gt;20&lt;BlockDuration&gt;
    &lt;BlockDuration&gt;20&lt;/BlockDuration&gt;
    &lt;Block/&gt;
  &lt;/BlockGroup&gt;
  ...
&lt;/Cluster&gt;

</sourcecode>

<ul spacing="compact">
<li>BlockGroup
</figure>
<figure><name><tt>BlockGroup</tt> with a frame that references two other frames, Frame That References Two Other Frames, with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;BlockGroup&gt;
    &lt;!-- References a Block 80 Track Ticks before this one --&gt;
    &lt;ReferenceBlock&gt;-80&lt;/ReferenceBlock&gt;
    &lt;!-- References a Block 40 Track Ticks after this one --&gt;
    &lt;ReferenceBlock&gt;40&lt;/ReferenceBlock&gt;
    &lt;Block/&gt;
  &lt;/BlockGroup&gt;
  ...
&lt;/Cluster&gt;

</sourcecode>
</figure>
<t>Intra-only video frames, such as the ones found in AV1 or VP9, can be decoded without any other
frame, but they don't reset the codec state. So Thus, seeking to these frames is not possible possible,
as the next frames may need frames that are not known from this seeking point.
Such intra-only frames <bcp14>MUST NOT</bcp14> be considered as keyframes keyframes, so the keyframe flag
<bcp14>MUST NOT</bcp14> be set in the <tt>SimpleBlock</tt> or a <tt>ReferenceBlock</tt> <bcp14>MUST</bcp14> be used
to signify the frame is not a RAP. The timestamp value of the <tt>ReferenceBlock</tt> <bcp14>MUST</bcp14>
be &quot;0&quot;, "0", meaning it's referencing itself.</t>

<ul spacing="compact">
<li>Intra-only frame not an RAP,
<figure><name>Intra-Only Frame (Not a RAP), with the EBML tree shown Tree Shown as XML:</li>
</ul> XML
</name>
<sourcecode type="xml">&lt;Cluster&gt; type="xml">
&lt;Cluster&gt;
  &lt;Timestamp&gt;123456&lt;/Timestamp&gt;
  &lt;BlockGroup&gt;
    &lt;!-- References itself to mark it should not be used as RAP --&gt;
    &lt;ReferenceBlock&gt;0&lt;/ReferenceBlock&gt;
    &lt;Block/&gt;
  &lt;/BlockGroup&gt;
  ...
&lt;/Cluster&gt;

</sourcecode>
</figure>
<t>Because a video <tt>SimpleBlock</tt> has less references information on references than a video <tt>BlockGroup</tt>,
it is possible to remux a video track using <tt>BlockGroup</tt> into a <tt>SimpleBlock</tt>,
as long as it doesn't use any other <tt>BlockGroup</tt> features than <tt>ReferenceBlock</tt>.</t>
</section>
</section>

<section anchor="timestamps"><name>Timestamps</name>
<t>Historically
<t>Historically, timestamps in Matroska were mistakenly called timecodes. The <tt>Timestamp Element</tt> <tt>Timestamp</tt> element
was called Timecode, the <tt>TimestampScale Element</tt> <tt>TimestampScale</tt> element was called TimecodeScale, the
<tt>TrackTimestampScale Element</tt>
<tt>TrackTimestampScale</tt> element was called TrackTimecodeScale TrackTimecodeScale, and the
<tt>ReferenceTimestamp Element</tt>
<tt>ReferenceTimestamp</tt> element was called ReferenceTimeCode.</t>

<section anchor="timestamp-ticks"><name>Timestamp Ticks</name>
<t>All timestamp values in Matroska are expressed in multiples of a tick.
They are usually stored as integers.
There are three types of ticks possible:</t> possible: Matroska Ticks, Segment Ticks, and Track Ticks.</t>

<section anchor="matroska-ticks"><name>Matroska Ticks</name>
<t>For such elements, the
<t>The timestamp value is stored directly in nanoseconds.</t>
<t>The elements storing values in Matroska Ticks/nanoseconds are:</t>

<ul spacing="compact">
<li><tt>TrackEntry\DefaultDuration</tt>; defined in <xref target="defaultduration-element"></xref></li>
<li><tt>TrackEntry\DefaultDecodedFieldDuration</tt>; defined in <xref target="defaultdecodedfieldduration-element"></xref></li>
<li><tt>TrackEntry\SeekPreRoll</tt>;

<ul>
<li><t><tt>TrackEntry\DefaultDuration</tt>; defined in <xref target="seekpreroll-element"></xref></li>
<li><tt>TrackEntry\CodecDelay</tt>; target="defaultduration-element"/></t>
</li>
<li><t><tt>TrackEntry\DefaultDecodedFieldDuration</tt>; defined in <xref target="codecdelay-element"></xref></li>
<li><tt>BlockGroup\DiscardPadding</tt>; target="defaultdecodedfieldduration-element"/></t>
</li>
<li><t><tt>TrackEntry\SeekPreRoll</tt>; defined in <xref target="discardpadding-element"></xref></li>
<li><tt>ChapterAtom\ChapterTimeStart</tt>; target="seekpreroll-element"/></t>
</li>
<li><t><tt>TrackEntry\CodecDelay</tt>; defined in <xref target="chaptertimestart-element"></xref></li>
<li><tt>ChapterAtom\ChapterTimeEnd</tt>; target="codecdelay-element"/></t>
</li>
<li><t><tt>BlockGroup\DiscardPadding</tt>; defined in <xref target="chaptertimeend-element"></xref></li>
<li><tt>CuePoint\CueTime</tt>; target="discardpadding-element"/></t>
</li>
<li><t><tt>ChapterAtom\ChapterTimeStart</tt>; defined in <xref target="cuetime-element"></xref></li>
<li><tt>CueReference\CueRefTime</tt>; target="chaptertimestart-element"/></t>
</li>
<li><t><tt>ChapterAtom\ChapterTimeEnd</tt>; defined in <xref target="cuetime-element"></xref></li> target="chaptertimeend-element"/></t>
</li>
</ul>
</section>

<section anchor="segment-ticks"><name>Segment Ticks</name>
<t>Elements in Segment Ticks involve the use of the <tt>TimestampScale Element</tt> <tt>TimestampScale</tt> element of the Segment <tt>Segment</tt> to get the timestamp in nanoseconds of the element, with the following formula:</t>

<artwork>timestamp

<artwork>
timestamp in nanosecond = element value * TimestampScale
</artwork>

<t>This allows storing for storage of smaller integer values in the elements.</t>
<t>When using the default value of <tt>TimestampScale</tt> of &quot;1,000,000&quot;, "1,000,000" for <tt>TimestampScale</tt>, one Segment Tick represents one millisecond.</t>
<t>The elements storing values in Segment Ticks are:</t>

<ul spacing="compact">
<li><tt>Cluster\Timestamp</tt>;

<ul>
<li><t><tt>Cluster\Timestamp</tt>; defined in <xref target="timestamp-element"></xref></li>
<li><tt>Info\Duration</tt> target="timestamp-element"/></t>
</li>
<li><t><tt>Info\Duration</tt> is stored as a floating-point floating-point, but the same formula applies; defined in <xref target="duration-element"></xref></li>
<li><tt>CuePoint\CueTrackPositions\CueDuration</tt>; target="duration-element"/></t>
</li>
<li><t><tt>CuePoint\CueTime</tt>; defined in <xref target="cuetime-element"/></t>
</li>
<li><t><tt>CuePoint\CueTrackPositions\CueDuration</tt>; defined in <xref target="cueduration-element"/></t>
</li>
<li><t><tt>CueReference\CueRefTime</tt>; defined in <xref target="cueduration-element"></xref></li> target="cuetime-element"/></t>
</li>
</ul>
</section>

<section anchor="track-ticks"><name>Track Ticks</name>
<t>Elements in Track Ticks involve the use of the <tt>TimestampScale Element</tt> <tt>TimestampScale</tt>
element of the Segment <tt>Segment</tt> and the <tt>TrackTimestampScale Element</tt> <tt>TrackTimestampScale</tt> element
of the Track <tt>Track</tt> to get the timestamp in nanoseconds of the element, with
the following formula:</t>

<artwork>timestamp

<artwork>
timestamp in nanoseconds =
    element value * TrackTimestampScale * TimestampScale

</artwork>
<t>This allows storing for storage of smaller integer values in the elements.
The resulting floating-point values of the timestamps are still expressed in nanoseconds.</t>
<t>When using the default values of "1,000,000" for <tt>TimestampScale</tt> and <tt>TrackTimestampScale</tt> of &quot;1,000,000&quot; and of &quot;1.0&quot; respectively, "1.0" for <tt>TrackTimestampScale</tt>, one Track Tick represents one millisecond.</t>
<t>The elements storing values in Track Ticks are:</t>

<ul spacing="compact">
<li><tt>Cluster\BlockGroup\Block</tt>

<ul>
<li><t><tt>Cluster\BlockGroup\Block</tt> and <tt>Cluster\SimpleBlock</tt> timestamps; detailed in <xref target="block-timestamps"></xref></li>
<li><tt>Cluster\BlockGroup\BlockDuration</tt>; target="block-timestamps"/></t>
</li>
<li><t><tt>Cluster\BlockGroup\BlockDuration</tt>; defined in <xref target="blockduration-element"></xref></li>
<li><tt>Cluster\BlockGroup\ReferenceBlock</tt>; target="blockduration-element"/></t>
</li>
<li><t><tt>Cluster\BlockGroup\ReferenceBlock</tt>; defined in <xref target="referenceblock-element"></xref></li> target="referenceblock-element"/></t>
</li>
</ul>
<t>When the <tt>TrackTimestampScale</tt> is interpreted as &quot;1.0&quot;, "1.0", Track Ticks are equivalent to Segment Ticks
and give an integer value in nanoseconds. This is the most common case as <tt>TrackTimestampScale</tt> is usually omitted.</t>
<t>A value of <tt>TrackTimestampScale</tt> other than &quot;1.0&quot; "1.0" <bcp14>MAY</bcp14>
be used to scale the timestamps more in tune with each Track <tt>Track</tt> sampling
frequency. For historical reasons, a lot of Matroska readers <tt>Matroska Readers</tt> don't
take the <tt>TrackTimestampScale</tt> value in into account.
So Thus, using a value
other than &quot;1.0&quot; "1.0" might not work in many places.</t>
</section>
</section>

<section anchor="block-timestamps"><name>Block Timestamps</name>
<t>A <tt>Block Element</tt> <tt>Block</tt> element and <tt>SimpleBlock Element</tt> <tt>SimpleBlock</tt> element timestamp is the
time when the decoded data of the first frame in the Block/SimpleBlock
<tt>Block</tt>/<tt>SimpleBlock</tt> <bcp14>MUST</bcp14> be presented, presented if the
track of that Block/SimpleBlock <tt>Block</tt>/<tt>SimpleBlock</tt> is selected for playback.
This is also known as the Presentation Timestamp (PTS).</t>
<t>The <tt>Block Element</tt> <tt>Block</tt> element and <tt>SimpleBlock Element</tt> <tt>SimpleBlock</tt> element store their
timestamps as signed integers, relative to the <tt>Cluster\Timestamp</tt>
value of the <tt>Cluster</tt> they are stored in.  To get the timestamp of a
<tt>Block</tt> or <tt>SimpleBlock</tt> in nanoseconds you have to use nanoseconds, the following formula:</t>

<artwork>( formula
is used:</t>

<artwork>
( Cluster\Timestamp + ( block timestamp * TrackTimestampScale ) ) *
TimestampScale

</artwork>
<t>The <tt>Block Element</tt> <tt>Block</tt> element and <tt>SimpleBlock Element</tt> <tt>SimpleBlock</tt> element store their timestamps as 16bit 16-bit signed integers,
allowing a range from &quot;-32768&quot; "-32768" to &quot;+32767&quot; "+32767" Track Ticks.
Although these values can be negative, when added to the <tt>Cluster\Timestamp</tt>, the resulting frame timestamp <bcp14>SHOULD NOT</bcp14> be negative.</t>
<t>When a <tt>CodecDelay Element</tt> <tt>CodecDelay</tt> element is set, its value <bcp14>MUST</bcp14> be substracted subtracted from each Block <tt>Block</tt> timestamp of that track.
To get the timestamp in nanoseconds of the first frame in a <tt>Block</tt> or <tt>SimpleBlock</tt>, the formula becomes:</t>

<artwork>(

<artwork>
( ( Cluster\Timestamp + ( block timestamp * TrackTimestampScale ) ) *
  TimestampScale ) - CodecDelay

</artwork>
<t>The resulting frame timestamp <bcp14>SHOULD NOT</bcp14> be negative.</t>
<t>During playback, when a frame has a negative timestamp, the content <bcp14>MUST</bcp14> be decoded by the decoder but not played to the user.</t>
</section>

<section anchor="timestampscale-rounding"><name>TimestampScale Rounding</name>
<t>The default Track Tick duration is one millisecond.</t>
<t>The <tt>TimestampScale</tt> is a floating-point value, which value that is usually 1.0.
"1.0". But when it's not, the multiplied
Block <tt>Block</tt> Timestamp is a
floating-point value in nanoseconds.  The <tt>Matroska Reader</tt>
<bcp14>SHOULD</bcp14> use the nearest rounding value in nanosecond nanoseconds to get the
proper nanosecond timestamp of a Block. <tt>Block</tt>. This allows some clever
<tt>TimestampScale</tt> values to have a more refined timestamp precision per
frame.</t>
</section>
</section>

<section anchor="language-codes"><name>Language Codes</name>
<t>Matroska from version versions 1 through 3 uses use language codes that can be either the 3 letters three-letter
bibliographic ISO-639-2 ISO 639-2 form <xref target="ISO639-2"></xref> target="ISO639-2"/> (like &quot;fre&quot; "fre" for French), French)
or such a language code followed by a dash and a country code for specialities in languages (like &quot;fre-ca&quot; "fre-ca" for Canadian French).
The <tt>ISO 639-2 Language Elements</tt> Language</tt> elements are &quot;Language Element&quot;, &quot;TagLanguage Element&quot;, <tt>Language</tt> element, <tt>TagLanguage</tt> element, and &quot;ChapLanguage Element&quot;.</t> <tt>ChapLanguage</tt> element.</t>
<t>Starting in Matroska version 4, the forms defined in either <xref target="ISO639-2"></xref> target="ISO639-2"/> or
<xref target="BCP47"></xref> target="RFC5646"/> <bcp14>MAY</bcp14> be used, although <tt>BCP 47</tt> the form in <xref target="RFC5646"/> is <bcp14>RECOMMENDED</bcp14>. The <tt>BCP 47 Language Elements</tt> <tt>Language</tt> elements in the <xref target="RFC5646"/> form
are &quot;LanguageBCP47 Element&quot;,
&quot;TagLanguageBCP47 Element&quot;, <tt>LanguageBCP47</tt> element, <tt>TagLanguageBCP47</tt> element, and &quot;ChapLanguageBCP47 Element&quot;.
<tt>ChapLanguageBCP47</tt> element. If a <tt>BCP 47 both an <xref target="ISO639-2"/> Language Element</tt> element and an <tt>ISO 639-2 <xref target="RFC5646"/> Language Element</tt> element are used within the same
<tt>Parent Element</tt>, then the <tt>ISO 639-2 Language Element</tt> <tt>Language</tt> element in the <xref target="ISO639-2"/> form <bcp14>MUST</bcp14>
be ignored and precedence given to the <tt>BCP 47 Language Element</tt>.</t> <tt>Language</tt> element in the <xref target="RFC5646"/> form.</t>
<t>In this document, "BCP47" in element names refers specifically to <xref
target="RFC5646"/>, which is part of BCP 47.</t>
</section>

<section anchor="country-codes"><name>Country Codes</name>
<t>Country codes are the <xref target="BCP47"></xref> target="RFC5646"/> two-letter region subtag, subtags, without the UK exception.</t>
</section>

<section anchor="encryption"><name>Encryption</name>
<t>This Matroska specification provides no interoperable solution for securing
the data container with any assurances of confidentiality, integrity,
authenticity, or to provide authorization. The <tt>ContentEncryption Element</tt> <tt>ContentEncryption</tt> element (<xref target="contentencryption-element"></xref>)
target="contentencryption-element"/>) and associated sub-fields (<xref target="contentencalgo-element"></xref>
target="contentencalgo-element"/> to <xref target="aessettingsciphermode-element"></xref>)
target="aessettingsciphermode-element"/>) are defined only for the benefit of
implementers to construct their own proprietary solution or as the basis for
further standardization activities.  How to use these fields to secure a
Matroska data container is out of scope, as are any related issues such as key
management and distribution.</t>
<t>A <tt>Matroska Reader</tt> who encounters containers that use the fields
defined in this section <bcp14>MUST</bcp14> rely on out-of-scope guidance to
decode the associated content.</t>
<t>Because encryption occurs within the <tt>Block Element</tt>, <tt>Block</tt> element, it is possible
to manipulate encrypted streams without decrypting them. The streams could
potentially be copied, deleted, cut, appended, or any number of other possible
editing techniques without decryption. The data can be used without having to
expose it or go through the decrypting process.</t>
<t>Encryption can also be layered within Matroska. This means that two completely different
types of encryption can be used, requiring two separate keys to be able to decrypt a stream.</t>
<t>Encryption information is stored in the <tt>ContentEncodings Element</tt> <tt>ContentEncodings</tt> element under the <tt>ContentEncryption Element</tt>.</t> <tt>ContentEncryption</tt> element.</t>

<t>For encryption systems sharing public/private keys, the creation of the keys and the exchange of keys
are not covered by this document. They have to be handled by the system using Matroska.</t>
<t>The algorithms described in <xref target="ContentEncAlgoValues"></xref> target="ContentEncAlgoValues"/> support
different modes of operations and key sizes.  The specification of these
parameters is required for a complete solution, solution but is out of scope of this
document and left to the proprietary implementations using them or subsequent
profiles of this document.</t>
<t>The <tt>ContentEncodingScope Element</tt> <tt>ContentEncodingScope</tt> element gives an idea of which part of
the track are encrypted.
But is encrypted, but each <tt>ContentEncAlgo Element</tt> <tt>ContentEncAlgo</tt> element and its sub elements like <tt>AESSettingsCipherMode</tt> really
sub-elements (like <tt>AESSettingsCipherMode</tt>) define exactly how the
encrypted track should be exactly interpreted.</t>
<t>An example of an extension that builds upon these security-related fields in this specification is <xref target="WebM-Enc"></xref>. target="WebM-Enc"/>.
It uses AES-CTR, <tt>ContentEncAlgo</tt> = 5 (<xref target="contentencalgo-element"></xref>) target="contentencalgo-element"/>), and <tt>AESSettingsCipherMode</tt> = 1 (<xref target="aessettingsciphermode-element"></xref>).</t> target="aessettingsciphermode-element"/>).</t>
<t>A <tt>Matroska Writer</tt> <bcp14>MUST NOT</bcp14> use insecure
cryptographic algorithms to create new archives or streams, but a <tt>Matroska
Reader</tt> <bcp14>MAY</bcp14> support these algorithms to read previously
made archives or stream.</t> streams.</t>
</section>

<section anchor="image-presentation"><name>Image Presentation</name>

<section anchor="cropping"><name>Cropping</name>
<t>The <tt>PixelCrop Elements</tt> <tt>PixelCrop</tt> elements (<tt>PixelCropTop</tt>,
<tt>PixelCropBottom</tt>, <tt>PixelCropRight</tt>, and <tt>PixelCropLeft</tt>)
indicate when, and by how much, encoded videos video frames <bcp14>SHOULD</bcp14> be
cropped for display.  These Elements elements allow edges of the frame that are not
intended for display, such display (such as the sprockets of a full-frame film scan or the VANC
Video ANCillary (VANC) area of a digitized analog videotape, videotape) to be stored but
hidden.  <tt>PixelCropTop</tt> and <tt>PixelCropBottom</tt> store an integer
of how many rows of pixels <bcp14>SHOULD</bcp14> be cropped from the top and
bottom of the image (respectively). image, respectively.  <tt>PixelCropLeft</tt> and
<tt>PixelCropRight</tt> store an integer of how many columns of pixels
<bcp14>SHOULD</bcp14> be cropped from the left and right of the image (respectively).</t> image,
respectively.</t>
<t>For example, a pillar-boxed video that stores a 1440x1080 visual image
within the center of a padded 1920x1080 encoded image may set both
<tt>PixelCropLeft</tt> and <tt>PixelCropRight</tt> to &quot;240&quot;, "240", so that a <tt>Matroska
Player</tt> should crop off 240 columns of pixels from the left and right of
the encoded image to present the image with the pillar-boxes hidden.</t>
<t>Cropping has to be performed before resizing and the display dimensions
given by <tt>DisplayWidth</tt>, <tt>DisplayHeight</tt> <tt>DisplayHeight</tt>, and
<tt>DisplayUnit</tt> apply to the already cropped already-cropped image.</t>
</section>

<section anchor="rotation"><name>Rotation</name>
<t>The ProjectionPoseRoll Element (see <xref target="projectionposeroll-element"></xref>) <tt>ProjectionPoseRoll</tt> element (<xref
target="projectionposeroll-element"/>) can be used to indicate that the image
from the associated video track <bcp14>SHOULD</bcp14> be rotated for
presentation.  For instance, the following representation example of the Projection Element <xref target="projection-element"></xref>) <tt>Projection</tt>
element (<xref target="projection-element"/>) and the ProjectionPoseRoll Element
<tt>ProjectionPoseRoll</tt> element represents a video track where the image
<bcp14>SHOULD</bcp14> be presented with a 90-degree counter-clockwise
rotation, with the EBML tree shown as XML :</t> XML:</t>
<figure><name>Rotation example. Example
</name>
<sourcecode type="xml">&lt;Projection&gt; type="xml">
&lt;Projection&gt;
  &lt;ProjectionPoseRoll&gt;90&lt;/ProjectionPoseRoll&gt;
&lt;/Projection&gt;

</sourcecode>
</figure>
</section>
</section>

<section anchor="segment-position"><name>Segment Position</name>
<t>The <tt>Segment Position</tt> of an <tt>Element</tt> element refers to the position of the
first octet of the <tt>Element ID</tt> of that <tt>Element</tt>, element, measured in octets,
from the beginning of the <tt>Element Data</tt> section of the containing <tt>Segment Element</tt>.
<tt>Segment</tt> element. In other words, the <tt>Segment Position</tt> of an
<tt>Element</tt>
element is the distance in octets from the beginning of its containing <tt>Segment Element</tt>
<tt>Segment</tt> element minus the size of the <tt>Element ID</tt> and
<tt>Element Data Size</tt> of that <tt>Segment Element</tt>. <tt>Segment</tt> element.  The <tt>Segment
Position</tt> of the first <tt>Child Element</tt> of the <tt>Segment Element</tt> <tt>Segment</tt>
element is 0.  An <tt>Element</tt> which element that is not stored within a <tt>Segment Element</tt>, <tt>Segment</tt>
element, such as the <tt>Elements</tt> elements of the <tt>EBML Header</tt>, do not have a
<tt>Segment Position</tt>.</t>

<section anchor="segment-position-exception"><name>Segment Position Exception</name>
<t><tt>Elements</tt>
<t>Elements that are defined to store a <tt>Segment Position</tt> <bcp14>MAY</bcp14> define reserved values to
indicate a special meaning.</t>
</section>

<section anchor="example-of-segment-position"><name>Example of Segment Position</name>
<t>This table presents an example of <tt>Segment Position</tt> by showing a hexadecimal representation
of a very small Matroska file with labels to show the offsets in octets. The file contains
a <tt>Segment Element</tt> <tt>Segment</tt> element with an <tt>Element ID</tt> of &quot;0x18538067&quot; "0x18538067" and a <tt>MuxingApp Element</tt> <tt>MuxingApp</tt> element with an <tt>Element ID</tt> of &quot;0x4D80&quot;.</t> "0x4D80".</t>
<artwork>
     0                             1                             2
     0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5  6  7  8  9  0
     +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
   0 |1A|45|DF|A3|8B|42|82|88|6D|61|74|72|6F|73|6B|61|
     ^ EBML Header
   0 |                                               |18|53|80|67|
                                                     ^ Segment ID
  20 |93|
     ^ Segment Data Size
  20 |  |15|49|A9|66|8E|4D|80|84|69|65|74|66|57|41|84|69|65|74|66|
        ^ Start of Segment data
  20 |                 |4D|80|84|69|65|74|66|57|41|84|69|65|74|66|
                       ^ MuxingApp start
</artwork>
<t>In the above example, the <tt>Element ID</tt> of the <tt>Segment Element</tt> <tt>Segment</tt> element is stored at offset 16,
the <tt>Element Data Size</tt> of the <tt>Segment Element</tt> <tt>Segment</tt> element is stored at offset 20, and the
<tt>Element Data</tt> of the <tt>Segment Element</tt> <tt>Segment</tt> element is stored at offset 21.</t>
<t>The <tt>MuxingApp Element</tt> <tt>MuxingApp</tt> element is stored at offset 26. Since the <tt>Segment Position</tt> of
an <tt>Element</tt> element is calculated by subtracting the position of the <tt>Element Data</tt> of
the containing <tt>Segment Element</tt> <tt>Segment</tt> element from the position of that <tt>Element</tt>, element, the <tt>Segment Position</tt>
of <tt>MuxingApp Element</tt> the <tt>MuxingApp</tt> element in the above example is '26 "26 - 21' 21" or '5'.</t> "5".</t>
</section>
</section>

<section anchor="linked-segments"><name>Linked Segments</name>
<t>Matroska provides several methods to link two or more <tt>Segment Elements</tt> <tt>Segment</tt>
elements together to create a <tt>Linked Segment</tt>. A <tt>Linked
Segment</tt> is a set of multiple <tt>Segments</tt> linked together into a
single presentation by using Hard Linking or Medium Linking.</t>
<t>All <tt>Segments</tt> within a <tt>Linked Segment</tt> <bcp14>MUST</bcp14> have a <tt>SegmentUUID</tt>.</t>
<t>All <tt>Segments</tt> within a <tt>Linked Segment</tt> <bcp14>SHOULD</bcp14> be stored within the same directory
or be accessible quickly accessible based on their <tt>SegmentUUID</tt>
in order to have a seamless transition between segments.</t>
<t>All <tt>Segments</tt> within a <tt>Linked Segment</tt> <bcp14>MAY</bcp14> set a <tt>SegmentFamily</tt> with a common value to make
it easier for a <tt>Matroska Player</tt> to know which <tt>Segments</tt> are meant to be played together.</t>

<t>The <tt>SegmentFilename</tt>, <tt>PrevFilename</tt> <tt>PrevFilename</tt>, and <tt>NextFilename</tt> elements <bcp14>MAY</bcp14> also give hints on
the original filenames that were used when the Segment <tt>Segment</tt> links were created, in case some <tt>SegmentUUID</tt> <tt>SegmentUUIDs</tt> are damaged.</t>

<section anchor="hard-linking"><name>Hard Linking</name>
<t>Hard Linking, also called splitting, "splitting", is the process of creating a <tt>Linked Segment</tt>
by linking multiple <tt>Segment Elements</tt> <tt>Segment</tt> elements using the <tt>NextUUID</tt> and <tt>PrevUUID</tt> Elements.</t> elements.</t>

<t>All <tt>Segments</tt> within a <tt>Hard Linked Segment</tt> <bcp14>MUST</bcp14> use the same <tt>Tracks</tt> list and <tt>TimestampScale</tt>.</t>
<t>Within a <tt>Linked Segment</tt>, the timestamps of <tt>Block</tt> and <tt>SimpleBlock</tt> <bcp14>MUST</bcp14> follow consecutively follow
the timestamps of <tt>Block</tt> and <tt>SimpleBlock</tt> from the previous <tt>Segment</tt> in linking order.</t>
<t>With Hard Linking, the chapters of any <tt>Segment</tt> within the <tt>Linked Segment</tt> <bcp14>MUST</bcp14> only reference the current <tt>Segment</tt>.
The <tt>NextUUID</tt> and <tt>PrevUUID</tt> reference the respective <tt>SegmentUUID</tt> values of the next and previous <tt>Segments</tt>.</t>
<t>The first <tt>Segment</tt> of a <tt>Linked Segment</tt> <bcp14>MUST NOT</bcp14> have a <tt>PrevUUID Element</tt>. <tt>PrevUUID</tt> element.
The last <tt>Segment</tt> of a <tt>Linked Segment</tt> <bcp14>MUST NOT</bcp14> have a <tt>NextUUID Element</tt>.</t> <tt>NextUUID</tt> element.</t>

<t>For each node of the chain of <tt>Segments</tt> of a <tt>Linked Segment</tt> Segment</tt>, at least one <tt>Segment</tt> <bcp14>MUST</bcp14> reference the other <tt>Segment</tt> within the chain.</t>
<t>In a chain of <tt>Segments</tt> of a <tt>Linked Segment</tt> Segment</tt>, the <tt>NextUUID</tt> always takes precedence over the <tt>PrevUUID</tt>.
So
Thus, if SegmentA has a <tt>NextUUID</tt> to SegmentB and SegmentB has a <tt>PrevUUID</tt> to SegmentC,
the link to use is <tt>NextUUID</tt> between SegmentA and SegmentB, and SegmentC is not part of the Linked Segment.</t> <tt>Linked Segment</tt>.</t>
<t>If SegmentB has a <tt>PrevUUID</tt> to SegmentA SegmentA, but SegmentA has no <tt>NextUUID</tt>, then the Matroska Player <tt>Matroska Player</tt>
<bcp14>MAY</bcp14> consider these two Segments <tt>Segments</tt> linked as SegmentA followed by SegmentB.</t>
<t>As an example, three <tt>Segments</tt> can be Hard Linked as a <tt>Linked Segment</tt> through
cross-referencing each other with <tt>SegmentUUID</tt>, <tt>PrevUUID</tt>, and <tt>NextUUID</tt>, <tt>NextUUID</tt> as shown in this table:</t>
<table anchor="hardLinkingUIDs"><name>Usual Hard Linking UIDs</name>
<thead>
<tr>
<th align="left">file name</th>
<th align="left"><tt>SegmentUUID</tt></th>
<th align="left"><tt>PrevUUID</tt></th>
<th align="left"><tt>NextUUID</tt></th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>start.mkv</tt></td>
<td align="left">71000c23cd310998 53fbc94dd984a5dd</td>
<td align="left">Invalid</td>
<td align="left">a77b3598941cb803 eac0fcdafe44fac9</td>
</tr>

<tr>
<td align="left"><tt>middle.mkv</tt></td>
<td align="left">a77b3598941cb803 eac0fcdafe44fac9</td>
<td align="left">71000c23cd310998 53fbc94dd984a5dd</td>
<td align="left">6c92285fa6d3e827 b198d120ea3ac674</td>
</tr>

<tr>
<td align="left"><tt>end.mkv</tt></td>
<td align="left">6c92285fa6d3e827 b198d120ea3ac674</td>
<td align="left">a77b3598941cb803 eac0fcdafe44fac9</td>
<td align="left">Invalid</td>
</tr>
</tbody>
</table><t>An other example where only the <tt>NextUUID</tt> Element element is used:</t>

<table anchor="hardLinkingWoPrevUUID"><name>Hard Linking without PrevUUID</name>
<thead>
<tr>
<th align="left">file name</th>
<th align="left"><tt>SegmentUUID</tt></th>
<th align="left"><tt>PrevUUID</tt></th>
<th align="left"><tt>NextUUID</tt></th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>start.mkv</tt></td>
<td align="left">71000c23cd310998 53fbc94dd984a5dd</td>
<td align="left">Invalid</td>
<td align="left">a77b3598941cb803 eac0fcdafe44fac9</td>
</tr>

<tr>
<td align="left"><tt>middle.mkv</tt></td>
<td align="left">a77b3598941cb803 eac0fcdafe44fac9</td>
<td align="left">n/a</td>
<td align="left">6c92285fa6d3e827 b198d120ea3ac674</td>
</tr>

<tr>
<td align="left"><tt>end.mkv</tt></td>
<td align="left">6c92285fa6d3e827 b198d120ea3ac674</td>
<td align="left">n/a</td>
<td align="left">Invalid</td>
</tr>
</tbody>
</table><t>An example where only the <tt>PrevUUID</tt> Element element is used:</t>

<table anchor="hardLinkingWoNextUUID"><name>Hard Linking without NextUUID</name>
<thead>
<tr>
<th align="left">file name</th>
<th align="left"><tt>SegmentUUID</tt></th>
<th align="left"><tt>PrevUUID</tt></th>
<th align="left"><tt>NextUUID</tt></th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>start.mkv</tt></td>
<td align="left">71000c23cd310998 53fbc94dd984a5dd</td>
<td align="left">Invalid</td>
<td align="left">n/a</td>
</tr>

<tr>
<td align="left"><tt>middle.mkv</tt></td>
<td align="left">a77b3598941cb803 eac0fcdafe44fac9</td>
<td align="left">71000c23cd310998 53fbc94dd984a5dd</td>
<td align="left">n/a</td>
</tr>

<tr>
<td align="left"><tt>end.mkv</tt></td>
<td align="left">6c92285fa6d3e827 b198d120ea3ac674</td>
<td align="left">a77b3598941cb803 eac0fcdafe44fac9</td>
<td align="left">Invalid</td>
</tr>
</tbody>
</table><t>In this
</table><t>An example where only the <tt>middle.mkv</tt> is using the <tt>PrevUUID</tt> and <tt>NextUUID</tt> Elements:</t> elements:</t>

<table anchor="hardLinkingMixedUIDs"><name>Hard Linking with mixed Mixed UID links</name> Links</name>
<thead>
<tr>
<th align="left">file name</th>
<th align="left"><tt>SegmentUUID</tt></th>
<th align="left"><tt>PrevUUID</tt></th>
<th align="left"><tt>NextUUID</tt></th>
</tr>
</thead>

<tbody>
<tr>
<td align="left"><tt>start.mkv</tt></td>
<td align="left">71000c23cd310998 53fbc94dd984a5dd</td>
<td align="left">Invalid</td>
<td align="left">n/a</td>
</tr>

<tr>
<td align="left"><tt>middle.mkv</tt></td>
<td align="left">a77b3598941cb803 eac0fcdafe44fac9</td>
<td align="left">71000c23cd310998 53fbc94dd984a5dd</td>
<td align="left">6c92285fa6d3e827 b198d120ea3ac674</td>
</tr>

<tr>
<td align="left"><tt>end.mkv</tt></td>
<td align="left">6c92285fa6d3e827 b198d120ea3ac674</td>
<td align="left">n/a</td>
<td align="left">Invalid</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="medium-linking"><name>Medium Linking</name>
<t>Medium Linking creates relationships between <tt>Segments</tt> using Ordered Chapters
<tt>Ordered Chapters</tt> (<xref target="editionflagordered"></xref>) target="editionflagordered"/>) and the
<tt>ChapterSegmentUUID Element</tt>.
<tt>ChapterSegmentUUID</tt> element. A <tt>Chapter Edition</tt> with Ordered Chapters
<tt>Ordered Chapters</tt> <bcp14>MAY</bcp14> contain
Chapter <tt>Chapters</tt>
elements that reference timestamp ranges from other <tt>Segments</tt>. The
<tt>Segment</tt> referenced by the Ordered Chapter <tt>Ordered Chapter</tt> via the <tt>ChapterSegmentUUID Element</tt>
<tt>ChapterSegmentUUID</tt> element <bcp14>SHOULD</bcp14> be played as part of
a Linked Segment.</t> <tt>Linked Segment</tt>.</t>
<t>The timestamps of Segment <tt>Segment</tt> content referenced by Ordered Chapters <tt>Ordered Chapters</tt>
<bcp14>MUST</bcp14> be adjusted according to the cumulative duration of the previous Ordered Chapters.</t> <tt>Ordered Chapters</tt>.</t>
<t>As an example example, a file named <tt>intro.mkv</tt> could have a
<tt>SegmentUUID</tt> of &quot;0xb16a58609fc7e60653a60c984fc11ead&quot;. "0xb16a58609fc7e60653a60c984fc11ead".  Another file
called <tt>program.mkv</tt> could use a Chapter Edition <tt>Chapter Edition</tt> that contains
two Ordered Chapters. <tt>Ordered Chapters</tt>.  The first chapter references the
<tt>Segment</tt> of <tt>intro.mkv</tt> with the use of a
<tt>ChapterSegmentUUID</tt>, <tt>ChapterSegmentEditionUID</tt>,
<tt>ChapterTimeStart</tt>, and optionally a an optional <tt>ChapterTimeEnd</tt> element.
The second chapter references content within the <tt>Segment</tt> of
<tt>program.mkv</tt>. A <tt>Matroska Player</tt> <bcp14>SHOULD</bcp14>
recognize the <tt>Linked Segment</tt> created by the use of
<tt>ChapterSegmentUUID</tt> in an enabled <tt>Edition</tt> and present the
reference content of the two <tt>Segments</tt> as a single presentation.</t>
<t>The <tt>ChapterSegmentUUID</tt> represents the Segment <tt>Segment</tt> that holds the content to play in place of the <tt>Linked Chapter</tt>.
The <tt>ChapterSegmentUUID</tt> <bcp14>MUST NOT</bcp14> be the <tt>SegmentUUID</tt> of its own <tt>Segment</tt>.</t>
<t>There are 2 two ways to use a chapter link:</t>

<ul>
<li><t>Linked-Duration linking,</t> linking</t>
</li>
<li><t>Linked-Edition linking</t>
</li>
</ul>

<section anchor="linked-duration"><name>Linked-Duration</name>
<t>A <tt>Matroska Player</tt> <bcp14>MUST</bcp14> play the content of the linked Segment
<tt>Linked Segment</tt> from the <tt>ChapterTimeStart</tt> until the
<tt>ChapterTimeEnd</tt> timestamp in place of the <tt>Linked Chapter</tt>.</t>
<t><tt>ChapterTimeStart</tt> and <tt>ChapterTimeEnd</tt> represent timestamps in the Linked Segment <tt>Linked Segment</tt> matching the value of <tt>ChapterSegmentUUID</tt>.
Their values <bcp14>MUST</bcp14> be in the range of the linked Segment <tt>Linked Segment</tt> duration.</t>
<t>The <tt>ChapterTimeEnd</tt> value <bcp14>MUST</bcp14> be set when using linked-duration Linked-Duration chapter linking.
<tt>ChapterSegmentEditionUID</tt> <bcp14>MUST NOT</bcp14> be set.</t>
</section>

<section anchor="linked-edition"><name>Linked-Edition</name>
<t>A <tt>Matroska Player</tt> <bcp14>MUST</bcp14> play the whole linked <tt>Edition</tt> <tt>Linked Edition</tt> of the linked Segment <tt>Linked Segment</tt> in place of the <tt>Linked Chapter</tt>.</t>

<t><tt>ChapterSegmentEditionUID</tt> represents a valid Edition <tt>Edition</tt> from the Linked Segment <tt>Linked Segment</tt> matching the value of <tt>ChapterSegmentUUID</tt>.</t>
<t>When using linked-edition Linked-Edition chapter linking. linking, <tt>ChapterTimeEnd</tt> is <bcp14>OPTIONAL</bcp14>.</t>
</section>
</section>
</section>

<section anchor="track-flags"><name>Track Flags</name>

<section anchor="default-flag"><name>Default flag</name> Flag</name>
<t>The &quot;default track&quot; Default flag is a hint for a <tt>Matroska Player</tt> indicating that a
given track <bcp14>SHOULD</bcp14> be eligible to be automatically selected as
the default track for a given language. If no tracks in a given language have
the default track Default flag set, then all tracks in that language are eligible for
automatic selection. This can be used to indicate that a track provides &quot;regular service&quot;
"regular service" that is suitable for users with default settings, as opposed
to specialized services, such as commentary, hearing-impaired captions, captions for users with hearing
impairments, or descriptive audio.</t>
<t>The <tt>Matroska Player</tt> <bcp14>MAY</bcp14> override the &quot;default track&quot; Default flag
for any reason, including user preferences to prefer tracks providing
accessibility services.</t>
</section>

<section anchor="forced-flag"><name>Forced flag</name> Flag</name>
<t>The &quot;forced&quot; Forced flag tells the <tt>Matroska Player</tt> that it
<bcp14>SHOULD</bcp14> display this subtitle track, even if user preferences
usually would not call for any subtitles to be displayed alongside the current selected audio track.
track that is currently selected. This can be used to indicate that a track
contains translations of onscreen text, on-screen text or of dialogue spoken in a different
language than the track's primary one.</t> language.</t>
</section>

<section anchor="hearing-impaired-flag"><name>Hearing-impaired flag</name> anchor="hearing-impaired-flag"><name>Hearing-Impaired Flag</name>
<t>The &quot;hearing impaired&quot; Hearing-Impaired flag tells the <tt>Matroska Player</tt> that it
<bcp14>SHOULD</bcp14> prefer this track when selecting a default track for a hearing-impaired user,
user with a hearing impairment and that it <bcp14>MAY</bcp14> prefer to select
a different track when selecting a default track for a non-hearing-impaired user.</t> user that is not
hearing impaired.</t>
</section>

<section anchor="visual-impaired-flag"><name>Visual-impaired flag</name> anchor="visual-impaired-flag"><name>Visual-Impaired Flag</name>
<t>The &quot;visual impaired&quot; Visual-Impaired flag tells the <tt>Matroska Player</tt> that it
<bcp14>SHOULD</bcp14> prefer this track when selecting a default track for a visually-impaired user,
user with a visual impairment and that it <bcp14>MAY</bcp14> prefer to select
a different track when selecting a default track for a non-visually-impaired user.</t> user that is not
visually impaired.</t>
</section>

<section anchor="descriptions-flag"><name>Descriptions flag</name> Flag</name>
<t>The &quot;descriptions&quot; Descriptions flag tells the <tt>Matroska Player</tt> that this track is
suitable to play via a text-to-speech system for a visually-impaired user, user with a visual
impairment and that it <bcp14>SHOULD NOT</bcp14> automatically select this
track when selecting a default track for a non-visually-impaired user.</t> user that is not visually
impaired.</t>
</section>

<section anchor="original-flag"><name>Original flag</name> Flag</name>
<t>The &quot;original&quot; Original flag tells the <tt>Matroska Player</tt> that this track is in
the original language, language and that it <bcp14>SHOULD</bcp14> prefer it this track if
configured to prefer original-language tracks of this track's type.</t>
</section>

<section anchor="commentary-flag"><name>Commentary flag</name> Flag</name>
<t>The &quot;commentary&quot; Commentary flag tells the <tt>Matroska Player</tt> that this track
contains commentary on the content.</t>
</section>

<section anchor="track-operation"><name>Track Operation</name>
<t><tt>TrackOperation</tt> allows combining for the combination of multiple tracks to make a virtual one. It uses
two separate system to combine tracks. One to create a 3D &quot;composition&quot; "composition" (left/right/background planes)
and one to simplify join two tracks together to make a single track.</t>
<t>A track created with <tt>TrackOperation</tt> is a proper track with a UID and all its flags.
However, the codec ID is meaningless because each &quot;sub&quot; "sub" track needs to be decoded by its
own decoder before the &quot;operation&quot; "operation" is applied. The <tt>Cues Elements</tt> <tt>Cues</tt> elements corresponding to such
a virtual track <bcp14>SHOULD</bcp14> be the union of the <tt>Cues Elements</tt> <tt>Cues</tt> elements for each of the tracks it's composed of (when the <tt>Cues</tt> are defined per track).</t>
<t>In the case of <tt>TrackJoinBlocks</tt>, the <tt>Block Elements</tt> <tt>Block</tt> elements (from
<tt>BlockGroup</tt> and <tt>SimpleBlock</tt>) of all the tracks
<bcp14>SHOULD</bcp14> be used as if they were defined for this new virtual
<tt>Track</tt>.  When two <tt>Block Elements</tt> <tt>Block</tt> elements have overlapping start or
end timestamps, it's up to the underlying system to either drop some of these
frames or render them the way they overlap.  This situation
<bcp14>SHOULD</bcp14> be avoided when creating such tracks tracks, as you can never
be sure of the end result on different platforms.</t>
</section>

<section anchor="overlay-track"><name>Overlay Track</name>
<t>Overlay tracks
<t>An overlay track <bcp14>SHOULD</bcp14> be rendered in the same channel as the track it's linked to.
When content is found in such a track, it <bcp14>SHOULD</bcp14> be played on the rendering channel
instead of the original track.</t>
</section>

<section anchor="multi-planar-and-3d-videos"><name>Multi-planar and 3D videos</name> Videos</name>
<t>There are two different ways to compress 3D videos: have each eye track in a separate track
and have one track have both eyes combined inside (which is more efficient, efficient compression-wise).
Matroska supports both ways.</t>
<t>For the single track single-track variant, there is the <tt>StereoMode Element</tt>, <tt>StereoMode</tt> element,
which defines how planes are assembled in the track (mono or left-right
combined). Odd values of StereoMode <tt>StereoMode</tt> means the left plane comes first
for more convenient reading. The pixel count of the track
(<tt>PixelWidth</tt>/<tt>PixelHeight</tt>) is the raw amount number of pixels, for example pixels (for
example, 3840x1080 for full HD side by side, side), and the
<tt>DisplayWidth</tt>/<tt>DisplayHeight</tt> in pixels is the amount number of pixels
for one plane (1920x1080 for that full HD stream).  Old stereo 3D movies were
displayed using anaglyph (cyan and red colors separated).  For compatibility
with such movies, there is a value of the StereoMode <tt>StereoMode</tt> that corresponds
to AnaGlyph.</t> anaglyph.</t>
<t>There is also a &quot;packed&quot; "packed" mode (values 13 and 14) which that consists of packing two frames together
in a <tt>Block</tt> using that uses lacing. The first frame is the left eye and the other frame is the right eye
(or vice versa). The frames <bcp14>SHOULD</bcp14> be decoded in that order and are possibly dependent
on each other (P and B frames).</t>
<t>For separate tracks, Matroska needs to define exactly which track does what.
<tt>TrackOperation</tt> with <tt>TrackCombinePlanes</tt> do does that. For more details look at details, see
<xref target="track-operation"></xref> target="track-operation"/> on how TrackOperation <tt>TrackOperation</tt> works.</t>
<t>The 3D support is still in infancy and may evolve to support more features.</t>
<t>The StereoMode <tt>StereoMode</tt> used to be part of Matroska v2 v2, but it didn't meet the
requirement for multiple tracks. There was also a bug in libmatroska
<xref target="libmatroska"/> prior to 0.9.0 that would save/read it as
<tt>0x53B9</tt> instead of <tt>0x53B8</tt>; see OldStereoMode <tt>OldStereoMode</tt> (<xref target="oldstereomode-element"></xref>). target="oldstereomode-element"/>). <tt>Matroska Readers</tt>
<bcp14>MAY</bcp14> support these legacy files by checking Matroska v2 or
<tt>0x53B9</tt>.  The older values of StereoMode <tt>StereoMode</tt> were 0: mono, 1: right eye, 2: left eye, 3: both eyes, 0 (mono), 1 (right eye),
2 (left eye), and 3 (both eyes); these are the only values that can be found
in OldStereoMode. <tt>OldStereoMode</tt>.  They are not compatible with the StereoMode <tt>StereoMode</tt> values found in
Matroska v3 and above.</t>
</section>
</section>

<section anchor="default-track-selection"><name>Default track selection</name> Track Selection</name>
<t>This section provides some example sets of Tracks <tt>Tracks</tt> and hypothetical
user settings, along with indications of which ones a similarly-configured similarly configured
<tt>Matroska Player</tt> <bcp14>SHOULD</bcp14> automatically select for
playback by default in such a situation. A player <bcp14>MAY</bcp14> provide
additional settings with more detailed controls for more nuanced
scenarios. These examples are provided as guidelines to illustrate the
intended usages of the various supported Track flags, <tt>Track</tt> flags and their
expected behaviors.</t>
<t>Track
<t><tt>Track</tt> names are shown in English for illustrative purposes; actual
files may have titles in the language of each track, track or provide titles in
multiple languages.</t>

<section anchor="audio-selection"><name>Audio Selection</name>
<t>Example track set:</t>
<table anchor="audioTrackSelection"><name>Audio Tracks for default selection</name> Default Selection</name>
<thead>
<tr>
<th>No.</th>
<th>Type</th>
<th>Lang</th>
<th>Layout</th>
<th>Original</th>
<th>Default</th>
<th>Other flags</th> Flags</th>
<th>Name</th>
</tr>
</thead>

<tbody>
<tr>
<td>1</td>
<td>Video</td>
<td>und</td>
<td>N/A</td>
<td>N/A</td>
<td>N/A</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>2</td>
<td>Audio</td>
<td>eng</td>
<td>5.1</td>
<td>1</td>
<td>1</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>3</td>
<td>Audio</td>
<td>eng</td>
<td>2.0</td>
<td>1</td>
<td>1</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>4</td>
<td>Audio</td>
<td>eng</td>
<td>2.0</td>
<td>1</td>
<td>0</td>
<td>Visual-impaired</td>
<td>Visual-Impaired</td>
<td>Descriptive audio</td>
</tr>

<tr>
<td>5</td>
<td>Audio</td>
<td>esp</td>
<td>5.1</td>
<td>0</td>
<td>1</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>6</td>
<td>Audio</td>
<td>esp</td>
<td>2.0</td>
<td>0</td>
<td>0</td>
<td>Visual-impaired</td>
<td>Visual-Impaired</td>
<td>Descriptive audio</td>
</tr>

<tr>
<td>7</td>
<td>Audio</td>
<td>eng</td>
<td>2.0</td>
<td>1</td>
<td>0</td>
<td>Commentary</td>
<td>Director's Commentary</td>
</tr>

<tr>
<td>8</td>
<td>Audio</td>
<td>eng</td>
<td>2.0</td>
<td>1</td>
<td>0</td>
<td>None</td>
<td>Karaoke</td>
</tr>
</tbody>
</table><t>Here we have
</table><t>The table above shows a file with 7 seven audio tracks, of which 5 are tracks -- five in English and 2 are two in Spanish.</t>
<t>The English tracks all have the Original flag, indicating that English is the original content language.</t>
<t>Generally
<t>Generally, the player will first consider the track languages: if languages. If the player has an option to prefer
original-language audio and the user has enabled it, then it should prefer one of the Original-flagged tracks. tracks with the Original flag.
If the user has configured to specifically prefer audio tracks in English or
Spanish, the player should select one of the tracks in the corresponding
language. The player may also wish to prefer an Original-flagged a track with the Original flag if
no tracks matching any of the user's explicitly-preferred explicitly preferred languages are
available.</t>
<t>Two of the tracks have the Visual-impaired Visual-Impaired flag. If the player has been configured to prefer such tracks,
it should select one; otherwise, it should avoid them if possible.</t>
<t>If selecting an English track, when other settings have left multiple possible options,
it may be useful to exclude the tracks that lack the Default flag: here, flag. Here, one provides descriptive service for
the visually impaired
individuals with visual impairments (which has its own flag and may be automatically selected by user configuration, configuration
but is unsuitable for users with default-configured players), one is a commentary track
(which has its own flag, which flag and the player may or may not have specialized handling for),
and the last contains karaoke versions of the music that plays during the film, which film (which is an unusual
specialized audio service that Matroska has no built-in support for indicating, so it's indicated
in the track name instead. instead). By not setting the Default flag on these specialized tracks, the file's author
hints that they should not be automatically selected by a default-configured player.</t>
<t>Having narrowed its choices down, our the example player now may have to select between tracks 2 and 3.
The only difference between these tracks is their channel layouts: 2 is 5.1 surround, while 3 is stereo.
If the player is aware that the output device is a pair of headphones or stereo speakers, it may wish
to prefer the stereo mix automatically. On the other hand, if it knows that the device is a surround system,
it may wish to prefer the surround mix.</t>
<t>If the player finishes analyzing all of the available audio tracks and finds that multiple seems more than one seem equally
and maximally preferable, it <bcp14>SHOULD</bcp14> default to the first of the group.</t>
</section>

<section anchor="subtitle-selection"><name>Subtitle selection</name> Selection</name>
<t>Example track set:</t>
<table anchor="subtitleTrackSelection"><name>Subtitle Tracks for default selection</name> Default Selection</name>
<thead>
<tr>
<th>No.</th>
<th>Type</th>
<th>Lang</th>
<th>Original</th>
<th>Default</th>
<th>Forced</th>
<th>Other flags</th> Flags</th>
<th>Name</th>
</tr>
</thead>

<tbody>
<tr>
<td>1</td>
<td>Video</td>
<td>und</td>
<td>N/A</td>
<td>N/A</td>
<td>N/A</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>2</td>
<td>Audio</td>
<td>fra</td>
<td>1</td>
<td>1</td>
<td>N/A</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>3</td>
<td>Audio</td>
<td>por</td>
<td>0</td>
<td>1</td>
<td>N/A</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>4</td>
<td>Subtitles</td>
<td>fra</td>
<td>1</td>
<td>1</td>
<td>0</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>5</td>
<td>Subtitles</td>
<td>fra</td>
<td>1</td>
<td>0</td>
<td>0</td>
<td>Hearing-impaired</td>
<td>Hearing-Impaired</td>
<td>Captions for the hearing-impaired</td> users with hearing impairments</td>
</tr>

<tr>
<td>6</td>
<td>Subtitles</td>
<td>por</td>
<td>0</td>
<td>1</td>
<td>0</td>
<td>None</td>
<td></td>
</tr>

<tr>
<td>7</td>
<td>Subtitles</td>
<td>por</td>
<td>0</td>
<td>0</td>
<td>1</td>
<td>None</td>
<td>Signs</td>
</tr>

<tr>
<td>8</td>
<td>Subtitles</td>
<td>por</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>Hearing-impaired</td>
<td>Hearing-Impaired</td>
<td>SDH</td>
</tr>
</tbody>
</table><t>Here we have 2
</table><t>The table above shows two audio tracks and 5 five subtitle tracks. As we can see, French is the original language.</t>
<t>We'll start by discussing the case where the user prefers French (or Original-language) original-language)
audio (or has explicitly selected the French audio track), track) and also prefers French subtitles.</t>
<t>In this case, if the player isn't configured to display captions when the audio matches their
preferred subtitle languages, the player doesn't need to select a subtitle track at all.</t>
<t>If the user <em>has</em> indicated that they want captions to be displayed, the selection simply
comes down to whether Hearing-impaired hearing-impaired subtitles are preferred.</t>
<t>The situation for a user who prefers Portuguese subtitles starts out somewhat analogous.
If they select the original French audio (either by explicit audio language preference,
preference for Original-language original-language tracks, or by explicitly selecting that track), then the
selection once again comes down to the hearing-impaired preference.</t>
<t>However, the case where the Portuguese audio track is selected has an important catch:
a Forced track in Portuguese is present. This may contain translations of onscreen on-screen text
from the video track, track or of portions of the audio that are not translated (music, for instance).
This means that even if the user's preferences wouldn't normally call for captions here,
the Forced track should be selected nonetheless, rather than selecting no track at all.
On the other hand, if the user's preferences <em>do</em> call for captions, the non-Forced tracks
should be preferred, as the Forced track will not contain captioning for the dialogue.</t>
</section>
</section>

<section anchor="chapters"><name>Chapters</name>
<t>The Matroska Chapters <tt>Chapters</tt> system can have multiple <tt>Editions</tt> <tt>Editions</tt>, and each <tt>Edition</tt> can consist of
<tt>Simple Chapters</tt> where a chapter start time is used as a marker in the timeline only. An
<tt>Edition</tt> can be more complex with <tt>Ordered Chapters</tt> where a chapter end time stamp timestamp is additionally
used or much more complex with <tt>Linked Chapters</tt>. The Matroska Chapters <tt>Chapters</tt> system can also have a menu
structure,
structure borrowed from the DVD menu DVD-menu system <xref target="DVD-Video"></xref>, target="DVD-Video"/> or have its own built-in Matroska menu structure.</t>

<section anchor="editionentry"><name>EditionEntry</name>
<t>The <tt>EditionEntry</tt> is also called an <tt>Edition</tt>.
An <tt>Edition</tt> contains a set of <tt>Edition</tt> flags and <bcp14>MUST</bcp14> contain at least one <tt>ChapterAtom Element</tt>.
Chapters <tt>ChapterAtom</tt> element.

<tt>Chapters</tt> are always inside an <tt>Edition</tt> (or a Chapter <tt>Chapter</tt> itself is part of an <tt>Edition</tt>).
Multiple Editions <tt>Editions</tt> are allowed. Some of these Editions <tt>Editions</tt> <bcp14>MAY</bcp14> be ordered and others not.</t>

<section anchor="editionflagdefault"><name>EditionFlagDefault</name>
<t>Only one <tt>Edition</tt> <bcp14>SHOULD</bcp14> have an <tt>EditionFlagDefault</tt> flag set to <tt>true</tt>.</t>
</section>

<section anchor="default-edition"><name>Default Edition</name>
<t>The <tt>Default Edition</tt> is the <tt>Edition</tt> that a <tt>Matroska Player</tt> <bcp14>SHOULD</bcp14> use for playback by default.</t>

<t>The first <tt>Edition</tt> with the <tt>EditionFlagDefault</tt> flag set to <tt>true</tt> is the <tt>Default Edition</tt>.</t>
<t>When all <tt>EditionFlagDefault</tt> flags are set to <tt>false</tt>, then the first <tt>Edition</tt>
is the <tt>Default Edition</tt>.</t>
<table anchor="defaultEditionAllDefault"><name>Default edition, all default</name> Edition, All Default</name>
<thead>
<tr>
<th align="left">Edition</th>
<th align="left">FlagDefault</th>
<th align="left">Default Edition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">Edition 1</td>
<td align="left">true</td>
<td align="left">X</td>
</tr>

<tr>
<td align="left">Edition 2</td>
<td align="left">true</td>
<td align="left"></td>
</tr>

<tr>
<td align="left">Edition 3</td>
<td align="left">true</td>
<td align="left"></td>
</tr>
</tbody>
</table><table anchor="defaultEditionNoDefault"><name>Default edition, no default</name> Edition, No Default</name>
<thead>
<tr>
<th align="left">Edition</th>
<th align="left">FlagDefault</th>
<th align="left">Default Edition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">Edition 1</td>
<td align="left">false</td>
<td align="left">X</td>
</tr>

<tr>
<td align="left">Edition 2</td>
<td align="left">false</td>
<td align="left"></td>
</tr>

<tr>
<td align="left">Edition 3</td>
<td align="left">false</td>
<td align="left"></td>
</tr>
</tbody>
</table><table anchor="defaultEditionWithDefault"><name>Default edition, with default</name> Edition, With Default</name>
<thead>
<tr>
<th align="left">Edition</th>
<th align="left">FlagDefault</th>
<th align="left">Default Edition</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">Edition 1</td>
<td align="left">false</td>
<td align="left"></td>
</tr>

<tr>
<td align="left">Edition 2</td>
<td align="left">true</td>
<td align="left">X</td>
</tr>

<tr>
<td align="left">Edition 3</td>
<td align="left">false</td>
<td align="left"></td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="editionflagordered"><name>EditionFlagOrdered</name>
<t>The <tt>EditionFlagOrdered Flag</tt> <tt>EditionFlagOrdered</tt> flag is a significant feature feature, as it
enables an <tt>Edition</tt> of <tt>Ordered Chapters</tt> which that defines and
arranges a virtual timeline rather than simply labeling points within the
timeline. For example, with <tt>Editions</tt> of <tt>Ordered Chapters</tt> Chapters</tt>, a
single <tt>Matroska file</tt> can present multiple edits of a film without
duplicating content.  Alternatively, if a videotape is digitized in full, one
<tt>Ordered Edition</tt> could present the full content (including colorbars,
countdown, slate, a feature presentation, and black frames), while another
<tt>Edition</tt> of <tt>Ordered Chapters</tt> can use <tt>Chapters</tt> that
only mark the intended presentation with the colorbars and other ancillary
visual information excluded. If an <tt>Edition</tt> of <tt>Ordered
Chapters</tt> is enabled, then the <tt>Matroska Player</tt>
<bcp14>MUST</bcp14> play those Chapters <tt>Chapters</tt> in their stored order from
the timestamp marked in the
<tt>ChapterTimeStart Element</tt> <tt>ChapterTimeStart</tt> element to the timestamp
marked in to <tt>ChapterTimeEnd Element</tt>.</t> <tt>ChapterTimeEnd</tt> element.</t>

<t>If the <tt>EditionFlagOrdered Flag</tt> <tt>EditionFlagOrdered</tt> flag evaluates to &quot;0&quot;, "0", <tt>Simple
Chapters</tt> are used and only the <tt>ChapterTimeStart</tt> of a
<tt>Chapter</tt> is used as a chapter mark to jump to the predefined point in
the timeline. With <tt>Simple Chapters</tt>, a <tt>Matroska Player</tt>
<bcp14>MUST</bcp14> ignore certain <tt>Chapter Elements</tt>. elements inside a <tt>Chapters</tt>
element. In that case case, these elements are informational only.</t>

<t>The following list shows the different Chapter <tt>Chapters</tt> elements only found in <tt>Ordered Chapters</tt>.</t>
<table anchor="orderedOnly"><name>elements only found in ordered chapters</name>
<thead>
<tr>
<th align="left">Ordered Chapter elements</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">ChapterAtom/ChapterSegmentUUID</td>
</tr>

<tr>
<td align="left">ChapterAtom/ChapterSegmentEditionUID</td>
</tr>

<tr>
<td align="left">ChapterAtom/ChapterTrack</td>
</tr>

<tr>
<td align="left">ChapterAtom/ChapProcess</td>
</tr>

<tr>
<td align="left">Info/ChapterTranslate</td>
</tr>

<tr>
<td align="left">TrackEntry/TrackTranslate</td>
</tr>
</tbody>
</table><t>Furthermore,

<ul>
<li><t><tt>ChapterAtom\ChapterSegmentUUID</tt></t>
</li>
<li><t><tt>ChapterAtom\ChapterSegmentEditionUID</tt></t>
</li>
<li><t><tt>ChapterAtom\ChapProcess</tt></t>
</li>
<li><t><tt>Info\ChapterTranslate</tt></t>
</li>
<li><t><tt>TrackEntry\TrackTranslate</tt></t>
</li>
</ul>
<t>Furthermore, there are other EBML <tt>Elements</tt> which elements that could be used if the <tt>EditionFlagOrdered</tt>
evaluates to &quot;1&quot;.</t> "1".</t>

<section anchor="ordered-edition-and-matroska-segment-linking"><name>Ordered-Edition and Matroska Segment-Linking</name>

<ul>
<li><t>Hard Linking: <tt>Ordered-Chapters</tt> supersedes Segment Linking</name>

<dl>
<dt>Hard Linking:</dt>
<dd><t><tt>Ordered Chapters</tt> supersede the <tt>Hard Linking</tt>.</t>
</li>
<li><t>Medium Linking: <tt>Ordered
</dd>
<dt>Medium Linking:</dt>
<dd><t><tt>Ordered Chapters</tt> are used in a normal way and can be combined
with the <tt>ChapterSegmentUUID</tt> element element, which establishes a link to another Segment.</t>
</li>
</ul> <tt>Segment</tt>.</t>
</dd>
</dl>
<t>See <xref target="linked-segments"></xref> target="linked-segments"/> on the Linked Segments <tt>Linked Segment</tt>s for more information
about <tt>Hard Linking</tt> and <tt>Medium Linking</tt>.</t>
</section>
</section>
</section>

<section anchor="chapteratom"><name>ChapterAtom</name>
<t>The <tt>ChapterAtom</tt> is also called a <tt>Chapter</tt>.</t>

<section anchor="chaptertimestart"><name>ChapterTimeStart</name>
<t>The
<t><tt>ChapterTimeStart</tt> is the timestamp of the start of <tt>Chapter</tt> with nanosecond accuracy, accuracy and is not scaled by TimestampScale. <tt>TimestampScale</tt>.
For <tt>Simple Chapters</tt> Chapters</tt>, this is the position of the chapter markers in the timeline.</t>
</section>

<section anchor="chaptertimeend"><name>ChapterTimeEnd</name>
<t>The
<t><tt>ChapterTimeEnd</tt> is the timestamp of the end of <tt>Chapter</tt>
with nanosecond accuracy, accuracy and is not scaled by TimestampScale. <tt>TimestampScale</tt>.  The
timestamp defined by the <tt>ChapterTimeEnd</tt> is not part of the
<tt>Chapter</tt>.  A <tt>Matroska Player</tt> calculates the duration of this
<tt>Chapter</tt> using the difference between the <tt>ChapterTimeEnd</tt> and
<tt>ChapterTimeStart</tt>.  The end timestamp <bcp14>MUST</bcp14> be greater
than or equal to the start timestamp.</t>
<t>When the <tt>ChapterTimeEnd</tt> timestamp is equal to the <tt>ChapterTimeStart</tt> timestamp,
the timestamps timestamp is included in the <tt>Chapter</tt>. It can be useful to put markers in
a file or add chapter commands with ordered chapter commands without having to play anything;
see <xref target="chapprocess-element"></xref>.</t> target="chapprocess-element"/>.</t>
<table anchor="ChapterTimeEndUsage"><name>ChapterTimeEnd usage possibilities</name> Usage Possibilities</name>
<thead>
<tr>
<th align="left">Chapter</th>
<th align="left">Start timestamp</th>
<th align="left">End timestamp</th>
<th align="left">Duration</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">Chapter 1</td>
<td align="left">0</td>
<td align="left">1000000000</td>
<td align="left">1000000000</td>
</tr>

<tr>
<td align="left">Chapter 2</td>
<td align="left">1000000000</td>
<td align="left">5000000000</td>
<td align="left">4000000000</td>
</tr>

<tr>
<td align="left">Chapter 3</td>
<td align="left">6000000000</td>
<td align="left">6000000000</td>
<td align="left">0</td>
</tr>

<tr>
<td align="left">Chapter 4</td>
<td align="left">9000000000</td>
<td align="left">8000000000</td>
<td align="left">Invalid (-1000000000)</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="nested-chapters"><name>Nested Chapters</name>
<t>A <tt>ChapterAtom</tt> element can contain other <tt>ChapterAtom</tt> elements.
That element is a <tt>Parent Chapter</tt> Chapter</tt>, and the <tt>ChapterAtom</tt> elements it contains are <tt>Nested Chapters</tt>.</t>
<t>Nested Chapters
<t><tt>Nested Chapters</tt> can be useful to tag small parts of a Segment <tt>Segment</tt> that already have tags or
add Chapter Codec commands on smaller parts of a Segment <tt>Segment</tt> that already have Chapter Codec commands.</t>
<t>The <tt>ChapterTimeStart</tt> of a <tt>Nested Chapter</tt> <bcp14>MUST</bcp14> be greater than or equal to the <tt>ChapterTimeStart</tt> of its <tt>Parent Chapter</tt>.</t>
<t>If the <tt>Parent Chapter</tt> of a <tt>Nested Chapter</tt> has a <tt>ChapterTimeEnd</tt>, the <tt>ChapterTimeStart</tt> of that <tt>Nested Chapter</tt>
<bcp14>MUST</bcp14> be smaller than or equal to the <tt>ChapterTimeEnd</tt> of the <tt>Parent Chapter</tt>.</t>
</section>

<section anchor="nested-chapters-in-ordered-chapters"><name>Nested Chapters in Ordered Chapters</name>
<t>The <tt>ChapterTimeEnd</tt> of the lowest level of <tt>Nested Chapters</tt> <bcp14>MUST</bcp14> be set for Ordered Chapters.</t> <tt>Ordered Chapters</tt>.</t>
<t>When used with Ordered Chapters, <tt>Ordered Chapters</tt>, the <tt>ChapterTimeEnd</tt> value of a <tt>Parent Chapter</tt> is useless for playback playback,
as the proper playback sections are described in its <tt>Nested Chapters</tt>.
The <tt>ChapterTimeEnd</tt> <bcp14>SHOULD NOT</bcp14> be set in <tt>Parent Chapters</tt> and <bcp14>MUST</bcp14> be ignored for playback.</t>
</section>

<section anchor="chapterflaghidden"><name>ChapterFlagHidden</name>
<t>Each Chapter <tt>Chapter</tt>'s <tt>ChapterFlagHidden</tt> flag works independently of parent chapters. <tt>Parent Chapters</tt>.
A <tt>Nested Chapter</tt> with a <tt>ChapterFlagHidden</tt> flag that evaluates to &quot;0&quot;
"0" remains visible in the user interface even if the <tt>Parent Chapter</tt> Chapter</tt>'s
<tt>ChapterFlagHidden</tt> flag is set to &quot;1&quot;.</t> "1".</t>
<table anchor="ChapterFlagHiddenNested"><name>ChapterFlagHidden nested visibility</name> Nested Visibility</name>
<thead>
<tr>
<th align="left">Chapter + Nested Chapter</th>
<th align="left">ChapterFlagHidden</th>
<th align="left">visible</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">Chapter 1</td>
<td align="left">0</td>
<td align="left">yes</td>
</tr>

<tr>
<td align="left">Nested Chapter 1.1</td>
<td align="left">0</td>
<td align="left">yes</td>
</tr>

<tr>
<td align="left">Nested Chapter 1.2</td>
<td align="left">1</td>
<td align="left">no</td>
</tr>

<tr>
<td align="left">Chapter 2</td>
<td align="left">1</td>
<td align="left">no</td>
</tr>

<tr>
<td align="left">Nested Chapter 2.1</td>
<td align="left">0</td>
<td align="left">yes</td>
</tr>

<tr>
<td align="left">Nested Chapter 2.2</td>
<td align="left">1</td>
<td align="left">no</td>
</tr>
</tbody>
</table></section>
</table>
</section>
</section>

<section anchor="menu-features"><name>Menu features</name> Features</name>
<t>The menu features are handled like a <tt>chapter codec</tt>. That means each codec has a type,
some private data data, and some data in the chapters.</t>
<t>The type of the menu system is defined by the <tt>ChapProcessCodecID</tt> parameter.
For now, only 2 two values are supported : supported: 0 matroska script, (Matroska Script) and 1 menu (menu borrowed from the DVD <xref target="DVD-Video"></xref>. target="DVD-Video"/>).
The private data depend on the type of menu system (stored in <tt>ChapProcessPrivate</tt>),
idem for the data stored in <tt>ChapProcessPrivate</tt> and
<tt>ChapProcessData</tt> depends on the chapters (stored in <tt>ChapProcessData</tt>).</t> <tt>ChapProcessCodecID</tt> value.</t>
<t>The menu system, as well as Chapter Codecs in general, can do perform actions on the <tt>Matroska Player</tt>
like Player</tt>, such as jumping to another Chapter <tt>Chapter</tt> or Edition, <tt>Edition</tt>, selecting different tracks tracks, and possibly more.
The scope of all the possibilities of Chapter Codecs is not covered in this document document, as it
depends on the Chapter Codec features and its integration in a <tt>Matroska Player</tt>.</t>
</section>

<section anchor="physical-types"><name>Physical Types</name>
<t>Each level can have different meanings for audio and video. The <tt>ORIGINAL_MEDIA_TYPE</tt> tag <xref target="MatroskaTags"></xref> target="I-D.ietf-cellar-tags"/> can be used to
specify a string for ChapterPhysicalEquiv = 60. Here is the list of possible levels for both audio and video:</t>
<table anchor="ChapterPhysicalEquivMeaning"><name>ChapterPhysicalEquiv meaning Meaning per track type</name> Track Type</name>
<thead>
<tr>
<th align="left">Value</th>
<th align="left">Audio</th>
<th align="left">Video</th>
<th align="left">Comment</th>
</tr>
</thead>

<tbody>
<tr>
<td align="left">70</td>
<td align="left">SET / PACKAGE</td>
<td align="left">SET / PACKAGE</td>
<td align="left">the collection of different media</td>
</tr>

<tr>
<td align="left">60</td>
<td align="left">CD / 12&quot; 12" / 10&quot; 10" / 7&quot; 7" / TAPE / MINIDISC / DAT</td>
<td align="left">DVD / VHS / LASERDISC</td>
<td align="left">the physical medium like a CD or a DVD</td>
</tr>

<tr>
<td align="left">50</td>
<td align="left">SIDE</td>
<td align="left">SIDE</td>
<td align="left">when the original medium (LP/DVD) has different sides</td>
</tr>

<tr>
<td align="left">40</td>
<td align="left">-</td>
<td align="left">LAYER</td>
<td align="left">another physical level on DVDs</td>
</tr>

<tr>
<td align="left">30</td>
<td align="left">SESSION</td>
<td align="left">SESSION</td>
<td align="left">as found on CDs and DVDs</td>
</tr>

<tr>
<td align="left">20</td>
<td align="left">TRACK</td>
<td align="left">-</td>
<td align="left">as found on audio CDs</td>
</tr>

<tr>
<td align="left">10</td>
<td align="left">INDEX</td>
<td align="left">-</td>
<td align="left">the first logical level of the side/medium</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="chapter-examples"><name>Chapter Examples</name>

<section anchor="example-1-basic-chaptering"><name>Example 1 : basic chaptering</name> 1: Basic Chaptering</name>
<t>In this example example, a movie is split in different chapters. It could also just be an
audio file (album) on in which each track corresponds to a chapter.</t>

<ul spacing="compact">
<li>00000 ms - 05000 ms : ms: Intro</li>
<li>05000 ms - 25000 ms : ms: Before the crime</li>
<li>25000 ms - 27500 ms : ms: The crime</li>
<li>27500 ms - 38000 ms : The killer arrested</li> ms: After the crime</li>
<li>38000 ms - 43000 ms : ms: Credits</li>
</ul>
<t>This would translate in the following matroska translates to Matroska form, with the EBML tree shown as XML :</t> follows in XML:</t>
<figure><name>Basic Chapters Example. Example
</name>
<sourcecode type="xml">&lt;Chapters&gt; type="xml">
&lt;Chapters&gt;
  &lt;EditionEntry&gt;
    &lt;EditionUID&gt;16603393396715046047&lt;/EditionUID&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;1193046&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;0&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;5000000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Intro&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;2311527&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;5000000000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;25000000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Before the crime&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Avant le crime&lt;/ChapString&gt;
        &lt;ChapLanguage&gt;fra&lt;/ChapLanguage&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;3430008&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;25000000000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;27500000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;The crime&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Le crime&lt;/ChapString&gt;
        &lt;ChapLanguage&gt;fra&lt;/ChapLanguage&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;4548489&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;27500000000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;38000000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;After the crime&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Apres le crime&lt;/ChapString&gt;
        &lt;ChapLanguage&gt;fra&lt;/ChapLanguage&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;5666960&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;38000000000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;43000000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Credits&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Generique&lt;/ChapString&gt;
        &lt;ChapLanguage&gt;fra&lt;/ChapLanguage&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
  &lt;/EditionEntry&gt;
&lt;/Chapters&gt;

</sourcecode>
</figure>
</section>

<section anchor="example-2-nested-chapters"><name>Example 2 : nested chapters</name> 2: Nested Chapters</name>
<t>In this example example, an (existing) album is split into different chapters, and one
of them contains another splitting.</t>

<section anchor="the-micronauts-bleep-to-bleep"><name>The Micronauts &quot;Bleep "Bleep To Bleep&quot;</name> Bleep"</name>

<ul spacing="compact">
<li><t>00:00 - 12:28 : 12:28: Baby Wants To wants to Bleep/Rock</t>

<ul spacing="compact">
<li>00:00 - 04:38 : 04:38: Baby wants to bleep (pt.1)</li>
<li>04:38 - 07:12 : 07:12: Baby wants to rock</li>
<li>07:12 - 10:33 : 10:33: Baby wants to bleep (pt.2)</li>
<li>10:33 - 12:28 : 12:28: Baby wants to bleep (pt.3)</li>
</ul></li>
<li>12:30 - 19:38 : 19:38: Bleeper_O+2</li>
<li>19:40 - 22:20 : 22:20: Baby wants to bleep (pt.4)</li>
<li>22:22 - 25:18 : 25:18: Bleep to bleep</li>
<li>25:20 - 33:35 : 33:35: Baby wants to bleep (k)</li>
<li>33:37 - 44:28 : 44:28: Bleeper</li>
</ul>
<t>This would translate in the following matroska translates to Matroska form, with the EBML tree shown as XML :</t> follows in XML:</t>
<figure><name>Nested Chapters Example. Example
</name>
<sourcecode type="xml">&lt;Chapters&gt; type="xml">
&lt;Chapters&gt;
  &lt;EditionEntry&gt;
    &lt;EditionUID&gt;1281690858003401414&lt;/EditionUID&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;1&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;0&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;748000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Baby wants to Bleep/Rock&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
      &lt;ChapterAtom&gt;
        &lt;ChapterUID&gt;2&lt;/ChapterUID&gt;
        &lt;ChapterTimeStart&gt;0&lt;/ChapterTimeStart&gt;
        &lt;ChapterTimeEnd&gt;278000000&lt;/ChapterTimeEnd&gt;
        &lt;ChapterDisplay&gt;
          &lt;ChapString&gt;Baby wants to bleep (pt.1)&lt;/ChapString&gt;
        &lt;/ChapterDisplay&gt;
      &lt;/ChapterAtom&gt;
      &lt;ChapterAtom&gt;
        &lt;ChapterUID&gt;3&lt;/ChapterUID&gt;
        &lt;ChapterTimeStart&gt;278000000&lt;/ChapterTimeStart&gt;
        &lt;ChapterTimeEnd&gt;432000000&lt;/ChapterTimeEnd&gt;
        &lt;ChapterDisplay&gt;
          &lt;ChapString&gt;Baby wants to rock&lt;/ChapString&gt;
        &lt;/ChapterDisplay&gt;
      &lt;/ChapterAtom&gt;
      &lt;ChapterAtom&gt;
        &lt;ChapterUID&gt;4&lt;/ChapterUID&gt;
        &lt;ChapterTimeStart&gt;432000000&lt;/ChapterTimeStart&gt;
        &lt;ChapterTimeEnd&gt;633000000&lt;/ChapterTimeEnd&gt;
        &lt;ChapterDisplay&gt;
          &lt;ChapString&gt;Baby wants to bleep (pt.2)&lt;/ChapString&gt;
        &lt;/ChapterDisplay&gt;
      &lt;/ChapterAtom&gt;
      &lt;ChapterAtom&gt;
        &lt;ChapterUID&gt;5&lt;/ChapterUID&gt;
        &lt;ChapterTimeStart&gt;633000000&lt;/ChapterTimeStart&gt;
        &lt;ChapterTimeEnd&gt;748000000&lt;/ChapterTimeEnd&gt;
        &lt;ChapterDisplay&gt;
          &lt;ChapString&gt;Baby wants to bleep (pt.3)&lt;/ChapString&gt;
        &lt;/ChapterDisplay&gt;
      &lt;/ChapterAtom&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;6&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;750000000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;1178500000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Bleeper_O+2&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;7&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;1180500000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;1340000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Baby wants to bleep (pt.4)&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;8&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;1342000000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;1518000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Bleep to bleep&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;9&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;1520000000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;2015000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Baby wants to bleep (k)&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
    &lt;ChapterAtom&gt;
      &lt;ChapterUID&gt;10&lt;/ChapterUID&gt;
      &lt;ChapterTimeStart&gt;2017000000&lt;/ChapterTimeStart&gt;
      &lt;ChapterTimeEnd&gt;2668000000&lt;/ChapterTimeEnd&gt;
      &lt;ChapterDisplay&gt;
        &lt;ChapString&gt;Bleeper&lt;/ChapString&gt;
      &lt;/ChapterDisplay&gt;
    &lt;/ChapterAtom&gt;
  &lt;/EditionEntry&gt;
&lt;/Chapters&gt;

</sourcecode>
</figure>
</section>
</section>
</section>
</section>

<section anchor="attachments-1"><name>Attachments</name>
<t>Matroska supports storage of related files and data in the <tt>Attachments Element</tt>
<tt>Attachments</tt> element (a <tt>Top-Level
Element</tt>). <tt>Attachment Elements</tt> <tt>Attachments</tt> elements can be used to store related
cover art, font files, transcripts, reports, error recovery files, picture, or pictures,
text-based annotations, copies of specifications, or other ancillary files
related to the <tt>Segment</tt>.</t>
<t><tt>Matroska Readers</tt> <bcp14>MUST NOT</bcp14> execute files stored as <tt>Attachment Elements</tt>.</t> <tt>Attachments</tt> elements.</t>

<section anchor="cover-art"><name>Cover Art</name>
<t>This section defines a set of guidelines for the storage of cover art in
Matroska files.  A <tt>Matroska Reader</tt> <bcp14>MAY</bcp14> use embedded
cover art to display a representational still-image depiction of the
multimedia contents of the Matroska file.</t>
<t>Only <xref target="JPEG"></xref> target="JPEG"/> and PNG <xref target="RFC2083"></xref> target="RFC2083"/> image formats <bcp14>SHOULD</bcp14> be used for cover art pictures.</t>
<t>There can be two different covers for a movie/album: a portrait style (e.g., a DVD case)
and a landscape style (e.g., a wide banner ad).</t>
<t>There can be two versions of the same cover, cover: the <tt>normal cover</tt> and
the <tt>small cover</tt>.  The dimension of the <tt>normal cover</tt>
<bcp14>SHOULD</bcp14> be 600 pixels on the smallest side -- for example, (e.g., 960x600 for
landscape, 600x800 for portrait, or 600x600 for square. square). The dimension of the
<tt>small cover</tt> <bcp14>SHOULD</bcp14> be 120 pixels on the smallest side -- for example,
(e.g., 192x120 or 120x160.</t> 120x160).</t>
<t>Versions of cover art can be differentiated by the filename, which is
stored in the
<tt>FileName Element</tt>. <tt>FileName</tt> element. The default filename of the
<tt>normal cover</tt> in square or portrait mode is
<tt>cover.(jpg|png)</tt>. When stored, the <tt>normal cover</tt>
<bcp14>SHOULD</bcp14> be the first Attachment <tt>Attachments</tt> element in storage

order. The <tt>small cover</tt> <bcp14>SHOULD</bcp14> be prefixed with &quot;small_&quot;,
"small_", such as <tt>small_cover.(jpg|png)</tt>. The landscape variant
<bcp14>SHOULD</bcp14> be suffixed with &quot;_land&quot;, "_land", such as
<tt>cover_land.(jpg|png)</tt>. The filenames are case-sensitive.</t>
<t>The following table provides examples of file names for cover art in Attachments.</t> <tt>Attachments</tt>.</t>
<table anchor="coverartFilenames"><name>Cover Art Filenames</name>
<thead>
<tr>
<th>FileName</th>
<th>File Name</th>
<th>Image Orientation</th>
<th>Pixel Length of Smallest Side</th>
</tr>
</thead>

<tbody>
<tr>
<td>cover.jpg</td>
<td>Portrait or square</td>
<td>600</td>
</tr>

<tr>
<td>small_cover.png</td>
<td>Portrait or square</td>
<td>120</td>
</tr>

<tr>
<td>cover_land.png</td>
<td>Landscape</td>
<td>600</td>
</tr>

<tr>
<td>small_cover_land.jpg</td>
<td>Landscape</td>
<td>120</td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="font-files"><name>Font files</name> Files</name>
<t>Font files <bcp14>MAY</bcp14> be added to a Matroska file as Attachments so that the font file may be used
to display an associated subtitle track. This allows the presentation of a Matroska file to be
consistent in various environments where the needed fonts might not be available on the local system.</t>
<t>Depending on the font format in question, each font file can contain multiple font variants.
Each font variant has a name which that  will be referred to as Font Name from now on.
This Font Name can be different from the Attachment's <tt>FileName</tt>, even when disregarding the extension.
In order to select a font for display, a Matroska player <tt>Matroska Player</tt> <bcp14>SHOULD</bcp14> consider both the Font Name
and the base name of the Attachment's FileName, <tt>FileName</tt>, preferring the former when there are multiple matches.</t>
<t>Subtitle codecs, such as SubStation Alpha (SSA/ASS), (SSA) and Advanced SubStation Alpha (ASS), usually refer to a font by its Font Name, not by its filename.
If none of the Attachments are a match for the Font Name, the Matroska player <tt>Matroska Player</tt> <bcp14>SHOULD</bcp14>
attempt to find a system font whose Font Name matches the one used in the subtitle track.</t>
<t>Since loading fonts temporarily can take a while, a Matroska player <tt>Matroska Player</tt> usually
loads or installs all the fonts found in attachments so they are ready to be used during playback.
Failure to use the font attachment might result in incorrect rendering of the subtitles.</t>
<t>If a selected subtitle track has some <tt>AttachmentLink</tt> elements, the player <bcp14>MAY</bcp14> restrict its font rendering to use only these fonts.</t>
<t>A Matroska player <tt>Matroska Player</tt> <bcp14>SHOULD</bcp14> handle the official font media types from <xref target="RFC8081"></xref> target="RFC8081"/> when the system can handle the type:</t>

<ul>
<li><t><tt>font/sfnt</tt>:
<li><t>font/sfnt: Generic SFNT Font Type,</t> Type</t>
</li>
<li><t><tt>font/ttf</tt>: TTF
<li><t>font/ttf: TrueType Font (TTF) Font Type,</t> Type</t>
</li>
<li><t><tt>font/otf</tt>:
<li><t>font/otf: OpenType Layout (OTF) Font Type,</t> Type</t>
</li>
<li><t><tt>font/collection</tt>:
<li><t>font/collection: Collection Font Type,</t> Type</t>
</li>
<li><t><tt>font/woff</tt>:
<li><t>font/woff: WOFF 1.0,</t> 1.0</t>
</li>
<li><t><tt>font/woff2</tt>:
<li><t>font/woff2: WOFF 2.0.</t> 2.0</t>
</li>
</ul>
<t>Fonts in Matroska existed long before <xref target="RFC8081"></xref>. target="RFC8081"/>. A few unofficial media types for fonts were used in existing files.
Therefore, it is <bcp14>RECOMMENDED</bcp14> for a Matroska player <tt>Matroska Player</tt> to support the following legacy media types for font attachments:</t>

<ul>
<li><t><tt>application/x-truetype-font</tt>: Truetype
<li><t>application/x-truetype-font: TrueType fonts, equivalent to <tt>font/ttf</tt> and sometimes <tt>font/otf</tt>,</t> <tt>font/otf</tt></t>
</li>
<li><t><tt>application/x-font-ttf</tt>: TTF
<li><t>application/x-font-ttf: TrueType fonts, equivalent to <tt>font/ttf</tt>,</t> <tt>font/ttf</tt></t>
</li>
<li><t><tt>application/vnd.ms-opentype</tt>:
<li><t>application/vnd.ms-opentype: OpenType Layout fonts, equivalent to <tt>font/otf</tt></t>
</li>
<li><t><tt>application/font-sfnt</tt>:
<li><t>application/font-sfnt: Generic SFNT Font Type, equivalent to <tt>font/sfnt</tt></t>
</li>
<li><t><tt>application/font-woff</tt>:
<li><t>application/font-woff: WOFF 1.0, equivalent to <tt>font/woff</tt></t>
</li>
</ul>
<t>There may also be some font attachments with the <tt>application/octet-stream</tt> media type.
In that case case, the Matroska player <tt>Matroska Player</tt> <bcp14>MAY</bcp14> try to guess the font type by checking the file extension of the <tt>AttachedFile\FileName</tt> string.
Common file extensions for fonts are:</t>

<ul>
<li><t><tt>.ttf</tt> for Truetype TrueType fonts, equivalent to <tt>font/ttf</tt>,</t> <tt>font/ttf</tt></t>
</li>
<li><t><tt>.otf</tt> for OpenType Layout fonts, equivalent to <tt>font/otf</tt>,</t> <tt>font/otf</tt></t>
</li>
<li><t><tt>.ttc</tt> for Collection fonts, equivalent to <tt>font/collection</tt></t>
</li>
</ul>
<t>The file extension check <bcp14>MUST</bcp14> be case-insensitive.</t>
<t>Matroska writers
<t><tt>Matroska Writers</tt> <bcp14>SHOULD</bcp14> use a valid font media type from <xref target="RFC8081"></xref> target="RFC8081"/> in the <tt>AttachedFile\FileMediaType</tt> of the font attachment.
They <bcp14>MAY</bcp14> use the media types found in older files when compatibility with older players is necessary.</t>
</section>
</section>

<section anchor="cues"><name>Cues</name>
<t>The <tt>Cues Element</tt> <tt>Cues</tt> element provides an index of certain <tt>Cluster Elements</tt> <tt>Cluster</tt>
elements to allow for optimized seeking to absolute timestamps within the
<tt>Segment</tt>. The <tt>Cues Element</tt> <tt>Cues</tt> element contains one or many <tt>CuePoint Elements</tt> which
<tt>CuePoint</tt> elements, each of which <bcp14>MUST</bcp14> reference an
absolute timestamp (via the
<tt>CueTime Element</tt>), <tt>CueTime</tt> element), a <tt>Track</tt> (via
the <tt>CueTrack Element</tt>), <tt>CueTrack</tt> element), and a <tt>Segment Position</tt> (via the <tt>CueClusterPosition Element</tt>).
<tt>CueClusterPosition</tt> element). Additional non-mandated Elements elements are
part of the <tt>CuePoint Element</tt> <tt>CuePoint</tt> element, such as <tt>CueDuration</tt>,
<tt>CueRelativePosition</tt>, <tt>CueCodecState</tt> <tt>CueCodecState</tt>, and others which that provide
any <tt>Matroska Reader</tt> with additional information to use in the
optimization of seeking performance.</t>

<section anchor="recommendations"><name>Recommendations</name>
<t>The following recommendations are provided to optimize Matroska performance.</t>

<ul>
<li><t>Unless Matroska is used as a live stream, it <bcp14>SHOULD</bcp14> contain a <tt>Cues Element</tt>.</t> <tt>Cues</tt> element.</t>
</li>
<li><t>For each video track, each keyframe <bcp14>SHOULD</bcp14> be referenced by a <tt>CuePoint Element</tt>.</t> <tt>CuePoint</tt> element.</t>
</li>
<li><t>It is <bcp14>RECOMMENDED</bcp14> to not reference non-keyframes of video tracks in <tt>Cues</tt> unless
it references a <tt>Cluster Element</tt> which <tt>Cluster</tt> element that contains a <tt>CodecState Element</tt> <tt>CodecState</tt> element but no keyframes.</t>
</li>
<li><t>For each subtitle track present, each subtitle frame <bcp14>SHOULD</bcp14> be referenced by a
<tt>CuePoint Element</tt>
<tt>CuePoint</tt> element with a <tt>CueDuration Element</tt>.</t> <tt>CueDuration</tt> element.</t>
</li>
<li><t>References to audio tracks <bcp14>MAY</bcp14> be skipped in <tt>CuePoint Elements</tt> <tt>CuePoint</tt> elements if a video track
is present. When included included, the <tt>CuePoint Elements</tt> <tt>CuePoint</tt> elements <bcp14>SHOULD</bcp14> reference audio keyframes
at most
once every 500 milliseconds.</t> milliseconds at most.</t>
</li>
<li><t>If the referenced frame is not stored within the first <tt>SimpleBlock</tt>, <tt>SimpleBlock</tt> or first
<tt>BlockGroup</tt> within its <tt>Cluster Element</tt>, <tt>Cluster</tt> element, then the <tt>CueRelativePosition Element</tt> <tt>CueRelativePosition</tt> element
<bcp14>SHOULD</bcp14> be written to reference where in the <tt>Cluster</tt> the reference frame is stored.</t>
</li>
<li><t>If a <tt>CuePoint Element</tt> <tt>CuePoint</tt> element references <tt>Cluster Element</tt> a <tt>Cluster</tt> element that includes a <tt>CodecState Element</tt>, <tt>CodecState</tt> element,
then that <tt>CuePoint Element</tt> <tt>CuePoint</tt> element <bcp14>MUST</bcp14> use a <tt>CueCodecState Element</tt>.</t> <tt>CueCodecState</tt> element.</t>
</li>
<li><t><tt>CuePoint Elements</tt>
<li><t><tt>CuePoint</tt> elements <bcp14>SHOULD</bcp14> be numerically sorted in storage order by the value of the <tt>CueTime Element</tt>.</t> <tt>CueTime</tt> element.</t>
</li>
</ul>
</section>
</section>

<section anchor="matroska-streaming"><name>Matroska Streaming</name>
<t>In Matroska, there are two kinds of streaming: file access and livestreaming.</t>

<section anchor="file-access"><name>File Access</name>
<t>File access can simply be reading a file located on your computer, but it also includes
accessing a file from an HTTP (web) server or CIFS Common Internet File System (CIFS) (Windows share) server. These protocols
are usually safe from reading errors errors, and seeking in the stream is possible. However,
when a file is stored far away or on a slow server, seeking can be an expensive operation
and should be avoided. The
When followed, the guidelines in <xref target="implementation-recommendations"></xref>, when followed, target="implementation-recommendations"/> help reduce the number of
seeking operations for regular playback and also have the playback start
quickly without
a needing to read lot of data needed to read first (like a <tt>Cues Element</tt>, <tt>Attachment Element</tt> <tt>Cues</tt> element,
<tt>Attachments</tt> element, or <tt>SeekHead Element</tt>).</t> <tt>SeekHead</tt> element).</t>

<t>Matroska, having a small overhead, is well suited for storing music/videos on file
servers without a big impact on the bandwidth used. Matroska does not require the index
to be loaded before playing, which allows playback to start very quickly. The index can
be loaded only when seeking is requested the first time.</t>
</section>

<section anchor="livestreaming"><name>Livestreaming</name>
<t>Livestreaming is the equivalent of television broadcasting on the internet. Internet. There are 2 two
families of servers for livestreaming: RTP/RTSP RTP / Real-Time Streaming Protocol (RTSP) and HTTP. Matroska is not meant to be
used over RTP. RTP already has timing and channel mechanisms that would be wasted if doubled
in Matroska. Additionally, having the same information at the RTP and Matroska level would
be a source of confusion if they do not match.
Livestreaming of Matroska over file-like protocols like HTTP, QUIC, etc. etc., is possible.</t>
<t>A live Matroska stream is different from a file because it usually has no
known end (only ending when the client disconnects). For this, all bits of the &quot;size&quot;
"size" portion of the <tt>Segment Element</tt> <tt>Segment</tt> element <bcp14>MUST</bcp14> be set to
1. Another option is to concatenate <tt>Segment Elements</tt> <tt>Segment</tt> elements with known
sizes, one after the other. This solution allows a change of codec/resolution
between each segment. For example, this allows for a switch between 4:3 and
16:9 in a television program.</t>
<t>When <tt>Segment Elements</tt> <tt>Segment</tt> elements are continuous, certain <tt>Elements</tt>, like elements (like
<tt>SeekHead</tt>, <tt>Cues</tt>, <tt>Chapters</tt>, and <tt>Attachments</tt>, <tt>Attachments</tt>)
<bcp14>MUST NOT</bcp14> be used.</t>
<t>It is possible for a <tt>Matroska Player</tt> to detect that a stream is
not seekable. If the stream has neither a <tt>SeekHead</tt> list nor a
<tt>Cues</tt> list at the beginning of the stream, it <bcp14>SHOULD</bcp14> be
considered non-seekable. Even though it is possible to seek forward in the
stream, it is <bcp14>NOT RECOMMENDED</bcp14>.</t>
<t>In the context of live radio or web TV, it is possible to &quot;tag&quot; "tag" the content while it is
playing. The <tt>Tags Element</tt> <tt>Tags</tt> element can be placed between <tt>Clusters</tt> each time it is necessary.
In that case, the new <tt>Tags Element</tt> <tt>Tags</tt> element <bcp14>MUST</bcp14> reset the previously encountered <tt>Tags Elements</tt> <tt>Tags</tt> elements
and use the new values instead.</t>

</section>
</section>

<section anchor="tags-1"><name>Tags</name>

<section anchor="tags-precedence"><name>Tags Precedence</name>
<t>Tags allow tagging all kinds of Matroska parts with very detailed metadata in multiple languages.</t>
<t>Some Matroska elements also contain their own string value value, like the Track Name track <tt>Name</tt> element (<xref target="name-element"></xref>) target="name-element"/>) or the Chapter String <tt>ChapString</tt> element (<xref target="chapstring-element"></xref>).</t> target="chapstring-element"/>).</t>

<t>The following Matroska elements can also be defined with tags:</t>

<ul>
<li><t>The Track Name Element track <tt>Name</tt> element (<xref target="name-element"></xref>) target="name-element"/>) corresponds to a tag with the TagTrackUID <tt>TagTrackUID</tt> (<xref target="tagtrackuid-element"></xref>) target="tagtrackuid-element"/>) set to the given track, a TagName <tt>TagName</tt> of <tt>TITLE</tt> (<xref target="tagname-element"></xref>) target="tagname-element"/>), and a TagLanguage <tt>TagLanguage</tt> (<xref target="taglanguage-element"></xref>) target="taglanguage-element"/>) or TagLanguageBCP47 <tt>TagLanguageBCP47</tt> (<xref target="taglanguagebcp47-element"></xref>) target="taglanguagebcp47-element"/>) of &quot;und&quot;.</t> "und".</t>

</li>
<li><t>The Chapter String Element <tt>ChapString</tt> element (<xref target="chapstring-element"></xref>) target="chapstring-element"/>) corresponds to a tag with the TagChapterUID <tt>TagChapterUID</tt> (<xref target="tagchapteruid-element"></xref>) target="tagchapteruid-element"/>) set to the same chapter UID, a TagName <tt>TagName</tt> of <tt>TITLE</tt> (<xref target="tagname-element"></xref>) target="tagname-element"/>), and a TagLanguage <tt>TagLanguage</tt> (<xref target="taglanguage-element"></xref>) target="taglanguage-element"/>) or TagLanguageBCP47 <tt>TagLanguageBCP47</tt> (<xref target="taglanguagebcp47-element"></xref>) target="taglanguagebcp47-element"/>) matching the ChapLanguage <tt>ChapLanguage</tt> (<xref target="chaplanguage-element"></xref>) target="chaplanguage-element"/>) or ChapLanguageBCP47 <tt>ChapLanguageBCP47</tt> (<xref target="chaplanguagebcp47-element"></xref>) target="chaplanguagebcp47-element"/>), respectively.</t>
</li>
<li><t>The FileDescription Element <tt>FileDescription</tt> element (<xref target="filedescription-element"></xref>) target="filedescription-element"/>) of an attachment corresponds to a tag with the TagAttachmentUID <tt>TagAttachmentUID</tt> (<xref target="tagattachmentuid-element"></xref>) target="tagattachmentuid-element"/>) set to the given attachment, a TagName <tt>TagName</tt> of <tt>TITLE</tt> (<xref target="tagname-element"></xref>) target="tagname-element"/>), and a TagLanguage <tt>TagLanguage</tt> (<xref target="taglanguage-element"></xref>) target="taglanguage-element"/>) or TagLanguageBCP47 <tt>TagLanguageBCP47</tt> (<xref target="taglanguagebcp47-element"></xref>) target="taglanguagebcp47-element"/>) of &quot;und&quot;.</t> "und".</t>

</li>
</ul>
<t>When both values exist in the file, the value found in Tags takes precedence over the value found in the original location of the element.
For example, if you have a <tt>TrackEntry\Name</tt> element and Tag a tag value <tt>TITLE</tt> for that track in a Matroska Segment, <tt>Segment</tt>, the Tag tag value string <bcp14>SHOULD</bcp14> be used and not instead of the <tt>TrackEntry\Name</tt> string to identify the track.</t>
<t>As the Tag element is optional, a lot of <tt>Matroska Readers</tt> do not
handle it and will not use the tags value when it's found.
So  Thus, for maximum
compatibility, it's usually better to put the strings in the
<tt>TrackEntry</tt>, <tt>ChapterAtom</tt> <tt>ChapterAtom</tt>, and <tt>Attachment</tt> <tt>Attachments</tt> elements
and keep the tags matching these values if tags are also used.</t>
</section>

<section anchor="tag-levels"><name>Tag Levels</name>
<t>Tag elements allow tagging information on multiple levels, with each level having a <tt>TargetTypeValue</tt> <xref target="targettypevalue-element"></xref>. (<xref target="targettypevalue-element"/>).
An element for a given <tt>TargetTypeValue</tt> also applies to the lower levels denoted by smaller <tt>TargetTypeValue</tt> values. If an upper value
doesn't apply to a level but the actual value to use is not known,
an empty <tt>TagString</tt> (<xref target="tagstring-element"></xref>) target="tagstring-element"/>) or an empty <tt>TagBinary</tt> (<xref target="tagbinary-element"></xref>) element target="tagbinary-element"/>) <bcp14>MUST</bcp14> be used as the tag value for this level.</t>
<t>See <xref target="MatroskaTags"></xref> target="I-D.ietf-cellar-tags"/> for more details on common tag names, types types, and descriptions.</t>
</section>
</section>

<section anchor="implementation-recommendations"><name>Implementation Recommendations</name>

<section anchor="cluster"><name>Cluster</name>
<t>It is <bcp14>RECOMMENDED</bcp14> that each individual <tt>Cluster Element</tt> contains <tt>Cluster</tt> element contain no more than
5
five seconds or 5 five megabytes of content.</t>
</section>

<section anchor="seekhead-1"><name>SeekHead</name>
<t>It is <bcp14>RECOMMENDED</bcp14> that the first <tt>SeekHead Element</tt> <tt>SeekHead</tt> element be followed by a <tt>Void Element</tt> <tt>Void</tt> element to
allow for the <tt>SeekHead Element</tt> <tt>SeekHead</tt> element to be expanded to cover new <tt>Top-Level Elements</tt>
that could be added to the Matroska file, such as <tt>Tags</tt>, <tt>Chapters</tt>, and <tt>Attachments</tt> Elements.</t> elements.</t>
<t>The size of this <tt>Void Element</tt> <tt>Void</tt> element should be adjusted depending on the Matroska file already having <tt>Tags</tt>,
<tt>Chapters</tt>, and <tt>Attachments</tt> Elements.</t> elements in the Matroska file.</t>
</section>

<section anchor="optimum-layouts"><name>Optimum Layouts</name>
<t>While there can be <tt>Top-Level Elements</tt> in any order, some ordering orderings of Elements elements are better than others.
Here are few
The following subsections detail optimum layouts for different use case:</t> cases.</t>

<section anchor="optimum-layout-for-a-muxer"><name>Optimum layout Layout for a muxer</name> Muxer</name>
<t>This is the basic layout muxers should be using for an efficient playback experience.</t> experience:</t>

<ul spacing="compact">
<li>SeekHead</li>
<li>Info</li>
<li>Tracks</li>
<li>Chapters</li>
<li>Attachments</li>
<li>Tags</li>
<li>Clusters</li>
<li>Cues</li>
<li><tt>SeekHead</tt></li>
<li><tt>Info</tt></li>
<li><tt>Tracks</tt></li>
<li><tt>Chapters</tt></li>
<li><tt>Attachments</tt></li>
<li><tt>Tags</tt></li>
<li><tt>Clusters</tt></li>
<li><tt>Cues</tt></li>
</ul>
</section>

<section anchor="optimum-layout-after-editing-tags"><name>Optimum layout Layout after editing tags</name> Editing Tags</name>
<t>When tags from the previous layout need to be extended, they are moved to the end with the extra information.
The location where the old tags were located is voided.</t>

<ul spacing="compact">
<li>SeekHead</li>
<li>Info</li>
<li>Tracks</li>
<li>Chapters</li>
<li>Attachments</li>
<li>Void</li>
<li>Clusters</li>
<li>Cues</li>
<li>Tags</li>
<li><tt>SeekHead</tt></li>
<li><tt>Info</tt></li>
<li><tt>Tracks</tt></li>
<li><tt>Chapters</tt></li>
<li><tt>Attachments</tt></li>
<li><tt>Void</tt></li>
<li><tt>Clusters</tt></li>
<li><tt>Cues</tt></li>
<li><tt>Tags</tt></li>
</ul>
</section>

<section anchor="optimum-layout-with-cues-at-the-front"><name>Optimum layout Layout with Cues at the front</name>
<t>Cues Front</name>
<t><tt>Cues</tt> are usually a big chunk of data referencing a lot of locations in the file.
For players
Players that want to seek in the file they need to seek to the end of the file
to access these locations. It is often better if they are placed early in the file.
On the other hand hand, that means players that don't intend to seek will have to read/skip
these data no matter what.</t>
<t>Because the Cues <tt>Cues</tt> reference locations further in the file, it's often complicated to
allocate the proper space for that element before all the locations are known.
Therefore, this layout is rarely used.</t> used:</t>

<ul spacing="compact">
<li>SeekHead</li>
<li>Info</li>
<li>Tracks</li>
<li>Chapters</li>
<li>Attachments</li>
<li>Tags</li>
<li>Cues</li>
<li>Clusters</li>
<li><tt>SeekHead</tt></li>
<li><tt>Info</tt></li>
<li><tt>Tracks</tt></li>
<li><tt>Chapters</tt></li>
<li><tt>Attachments</tt></li>
<li><tt>Tags</tt></li>
<li><tt>Cues</tt></li>
<li><tt>Clusters</tt></li>
</ul>
</section>

<section anchor="optimum-layout-for-livestreaming"><name>Optimum layout Layout for livestreaming</name> Livestreaming</name>
<t>In Livestreaming livestreaming (<xref target="livestreaming"></xref>) target="livestreaming"/>), only a few elements make sense. SeekHead For example, <tt>SeekHead</tt> and Cues <tt>Cues</tt> are useless for example. useless.
All elements other than the Clusters <tt>Clusters</tt> <bcp14>MUST</bcp14> be placed before the Clusters.</t> <tt>Clusters</tt>.</t>

<ul spacing="compact">
<li>Info</li>
<li>Tracks</li>
<li>Attachments
<li><tt>Info</tt></li>
<li><tt>Tracks</tt></li>
<li><tt>Attachments</tt> (rare)</li>
<li>Tags</li>
<li>Clusters</li>
<li><tt>Tags</tt></li>
<li><tt>Clusters</tt></li>
</ul>
</section>
</section>
</section>

<section anchor="security-considerations"><name>Security Considerations</name>
<t>Matroska inherits security considerations from EBML.</t> EBML <xref target="RFC8794"/>.</t>
<t>Attacks on a <tt>Matroska Reader</tt> could include:</t>
<ul>
<li><t>Storage of an arbitrary and potentially executable data within an <tt>Attachment Element</tt>. <tt>Attachments</tt> element.

<tt>Matroska Readers</tt> that extract or use data from Matroska Attachments <tt>Matroska Attachments</tt> <bcp14>SHOULD</bcp14>
check that the data adheres to expectations or not use the attachement.</t> attachment.</t>
</li>
<li><t>A <tt>Matroska Attachment</tt> with an inaccurate media type.</t>
</li>
<li><t>Damage to the Encryption and Compression fields (<xref target="encryption"></xref>) target="encryption"/>) that would result in bogus binary data
interpreted by the decoder.</t>
</li>
<li><t>Chapter Codecs running unwanted commands on the host system.</t>
</li>
</ul>
<t>The same error handling done for EBML applies to Matroska files.
Particular error handling is not covered in this specification specification, as this is
depends on the goal of the <tt>Matroska Readers</tt>.
It is up to the decision of the
<tt>Matroska Readers</tt> on decide how to handle the errors if whether or not they are
recoverable in their code or not. code.
For example, if the checksum of the <tt>\Segment\Tracks</tt> is invalid invalid, some
could decide to try to read the data anyway, some will just reject the file,
and most will not even check it.</t>
<t><tt>Matroska Reader</tt> implementations need to be robust against malicious payloads. Those related to denial of service are outlined in Section 2.1 of [RFC4732].<br />
Although <xref target="RFC4732" sectionFormat="of" section="2.1"/>.</t>
<t>Although rarer, the same may apply to a <tt>Matroska Writer</tt>.  Malicious stream data

must not cause the Writer <tt>Matroska Writer</tt> to misbehave, as this might allow an attacker access
to transcoding gateways.</t>
<t>As an audio and visual audio/video container format, a Matroska file or stream will
potentially encapsulate numerous byte streams created with a variety of
codecs.  Implementers will need to consider the security considerations of
these encapsulated formats.</t>
</section>

<section anchor="iana-considerations"><name>IANA Considerations</name>

<section anchor="matroska-element-ids-registry"><name>Matroska Element IDs Registry</name>
<t>This document creates
<t>IANA has created a new IANA registry called the &quot;Matroska "Matroska Element IDs&quot; IDs"
registry.</t>
<t>To register a new Element ID in this registry, one needs an Element ID, an
Element Name, a Change Controller (IETF or email of registrant) Controller, and an
optional Reference to a document describing the Element ID.</t>
<t>Element IDs are encoded
using the VINT mechanism described in Section 4 of <xref target="RFC8794"></xref> target="RFC8794" sectionFormat="of" section="4"/> and can be between
one and five octets long. Five-octet-long Five-octet Element IDs are possible
only if declared in the EBML header.</t> Header.</t>
<t>Element IDs are described in Section 5 of <xref target="RFC8794"></xref> target="RFC8794" sectionFormat="of" section="5"/>, with errata 7189 the changes in <xref target="Err7189"/> and 7191.</t> <xref target="Err7191"/>.</t>
<t>One-octet Matroska Element IDs (range 0x80-0xFE) are to be allocated according to the &quot;RFC Required&quot; "RFC Required" policy <xref target="RFC8126"></xref>.</t> target="RFC8126"/>.</t>
<t>Two-octet Matroska Element IDs (range 0x407F-0x7FFE) are to be allocated according to the &quot;Specification Required&quot; "Specification Required" policy <xref target="RFC8126"></xref>.</t> target="RFC8126"/>.</t>
<t>Two-octet Matroska Element IDs between 0x0100 and 0x407E are not valid for
use as an Element ID.</t>
<t>Three-octet (range 0x203FFF-0x3FFFFE) and four-octet Matroska Element IDs (range 0x101FFFFF-0x1FFFFFFE) are to be allocated according to the &quot;First "First Come First Served&quot; Served" policy <xref target="RFC8126"></xref>.</t> target="RFC8126"/>.</t>
<t>Three-octet Matroska Element IDs between 0x010000 and 0x203FFE are not valid for use as an Element ID.</t>
<t>Four-octet Matroska Element IDs between 0x01000000 and 0x101FFFFE are not valid for use as an Element ID.</t>
<t>The allowed values in the Elements IDs "Matroska Element IDs" registry are similar to the ones found
in the EBML "EBML Element IDs IDs" registry defined in Section 17.1 of <xref target="RFC8794"></xref>.</t> target="RFC8794" sectionFormat="of" section="17.1"/>.</t>
<t>EBML Element IDs defined for the EBML Header -- as defined in Section 17.1 of <xref target="RFC8794"></xref> target="RFC8794" sectionFormat="of" section="17.1"/> -- <bcp14>MUST NOT</bcp14> be used as Matroska Element IDs.</t>
<t>Given the scarcity of the One-octet one-octet Element IDs, they should only be created
to save space for elements found many times in a file.
For file (for example, within a BlockGroup <tt>BlockGroup</tt>
or Chapters. <tt>Chapters</tt>). The Four-octet four-octet Element IDs are mostly for synchronization of
large elements.  They should only be used for such high level high-level elements.
Elements that are not expected to be used often should use Three-octet three-octet Element
IDs.</t>
<t>Elements found in <xref target="annex-a-historic-deprecated-elements"></xref> target="appendix-a-historic-deprecated-elements"/> have an assigned Matroska Element ID for historical reasons.
These elements are not in use and <bcp14>SHOULD NOT</bcp14> be reused unless there is are no other IDs available with the desired size.
Such IDs are considered marked as <tt>reclaimed</tt> to "Reclaimed" in the IANA registry "Matroska Element IDs" registry, as they could be used for other things in the future.</t>
<t>Matroska Element IDs Values found in this document are assigned as
<t><xref target="iana-table"/> shows the initial values as follows:</t>
<table><name>IDs and Names contents of the
"Matroska Element IDs" registry. The Change Controller for Matroska the initial
entries is the IETF.</t>
<table anchor="iana-table"><name>Initial Contents of "Matroska Element IDs assigned by this document
</name> IDs" Registry</name>
<thead>
<tr>
<th align="right">Element ID</th>
<th align="left">Element Name</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0x80</td>
<td align="left">ChapterDisplay</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapterdisplay-element"></xref></td> target="chapterdisplay-element"/></td>
</tr>

<tr>
<td align="right">0x83</td>
<td align="left">TrackType</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tracktype-element"></xref></td> target="tracktype-element"/></td>
</tr>

<tr>
<td align="right">0x85</td>
<td align="left">ChapString</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapstring-element"></xref></td> target="chapstring-element"/></td>
</tr>

<tr>
<td align="right">0x86</td>
<td align="left">CodecID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="codecid-element"></xref></td> target="codecid-element"/></td>
</tr>

<tr>
<td align="right">0x88</td>
<td align="left">FlagDefault</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flagdefault-element"></xref></td> target="flagdefault-element"/></td>
</tr>

<tr>
<td align="right">0x8E</td>
<td align="left">Slices</td>
<td align="left">Reclaimed (<xref target="slices-element"></xref>)</td> (RFC 9559, <xref target="slices-element"/>)</td>
</tr>

<tr>
<td align="right">0x91</td>
<td align="left">ChapterTimeStart</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaptertimestart-element"></xref></td> target="chaptertimestart-element"/></td>
</tr>

<tr>
<td align="right">0x92</td>
<td align="left">ChapterTimeEnd</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaptertimeend-element"></xref></td> target="chaptertimeend-element"/></td>
</tr>

<tr>
<td align="right">0x96</td>
<td align="left">CueRefTime</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cuereftime-element"></xref></td> target="cuereftime-element"/></td>
</tr>

<tr>
<td align="right">0x97</td>
<td align="left">CueRefCluster</td>
<td align="left">Reclaimed (<xref target="cuerefcluster-element"></xref>)</td> (RFC 9559, <xref target="cuerefcluster-element"/>)</td>
</tr>

<tr>
<td align="right">0x98</td>
<td align="left">ChapterFlagHidden</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapterflaghidden-element"></xref></td> target="chapterflaghidden-element"/></td>
</tr>

<tr>
<td align="right">0x9A</td>
<td align="left">FlagInterlaced</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flaginterlaced-element"></xref></td> target="flaginterlaced-element"/></td>
</tr>

<tr>
<td align="right">0x9B</td>
<td align="left">BlockDuration</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockduration-element"></xref></td> target="blockduration-element"/></td>
</tr>

<tr>
<td align="right">0x9C</td>
<td align="left">FlagLacing</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flaglacing-element"></xref></td> target="flaglacing-element"/></td>
</tr>

<tr>
<td align="right">0x9D</td>
<td align="left">FieldOrder</td>
<td align="left">Described in align="left">RFC 9559, <xref target="fieldorder-element"></xref></td> target="fieldorder-element"/></td>
</tr>

<tr>
<td align="right">0x9F</td>
<td align="left">Channels</td>
<td align="left">Described in align="left">RFC 9559, <xref target="channels-element"></xref></td> target="channels-element"/></td>
</tr>

<tr>
<td align="right">0xA0</td>
<td align="left">BlockGroup</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockgroup-element"></xref></td> target="blockgroup-element"/></td>
</tr>

<tr>
<td align="right">0xA1</td>
<td align="left">Block</td>
<td align="left">Described in align="left">RFC 9559, <xref target="block-element"></xref></td> target="block-element"/></td>
</tr>

<tr>
<td align="right">0xA2</td>
<td align="left">BlockVirtual</td>
<td align="left">Reclaimed (<xref target="blockvirtual-element"></xref>)</td> (RFC 9559, <xref target="blockvirtual-element"/>)</td>
</tr>

<tr>
<td align="right">0xA3</td>
<td align="left">SimpleBlock</td>
<td align="left">Described in align="left">RFC 9559, <xref target="simpleblock-element"></xref></td> target="simpleblock-element"/></td>
</tr>

<tr>
<td align="right">0xA4</td>
<td align="left">CodecState</td>
<td align="left">Described in align="left">RFC 9559, <xref target="codecstate-element"></xref></td> target="codecstate-element"/></td>
</tr>

<tr>
<td align="right">0xA5</td>
<td align="left">BlockAdditional</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockadditional-element"></xref></td> target="blockadditional-element"/></td>
</tr>

<tr>
<td align="right">0xA6</td>
<td align="left">BlockMore</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockmore-element"></xref></td> target="blockmore-element"/></td>
</tr>

<tr>
<td align="right">0xA7</td>
<td align="left">Position</td>
<td align="left">Described in align="left">RFC 9559, <xref target="position-element"></xref></td> target="position-element"/></td>
</tr>

<tr>
<td align="right">0xAA</td>
<td align="left">CodecDecodeAll</td>
<td align="left">Reclaimed (<xref target="codecdecodeall-element"></xref>)</td> (RFC 9559, <xref target="codecdecodeall-element"/>)</td>
</tr>

<tr>
<td align="right">0xAB</td>
<td align="left">PrevSize</td>
<td align="left">Described in align="left">RFC 9559, <xref target="prevsize-element"></xref></td> target="prevsize-element"/></td>
</tr>

<tr>
<td align="right">0xAE</td>
<td align="left">TrackEntry</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackentry-element"></xref></td> target="trackentry-element"/></td>
</tr>

<tr>
<td align="right">0xAF</td>
<td align="left">EncryptedBlock</td>
<td align="left">Reclaimed (<xref target="encryptedblock-element"></xref>)</td> (RFC 9559, <xref target="encryptedblock-element"/>)</td>
</tr>

<tr>
<td align="right">0xB0</td>
<td align="left">PixelWidth</td>
<td align="left">Described in align="left">RFC 9559, <xref target="pixelwidth-element"></xref></td> target="pixelwidth-element"/></td>
</tr>

<tr>
<td align="right">0xB2</td>
<td align="left">CueDuration</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cueduration-element"></xref></td> target="cueduration-element"/></td>
</tr>

<tr>
<td align="right">0xB3</td>
<td align="left">CueTime</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cuetime-element"></xref></td> target="cuetime-element"/></td>
</tr>

<tr>
<td align="right">0xB5</td>
<td align="left">SamplingFrequency</td>
<td align="left">Described in align="left">RFC 9559, <xref target="samplingfrequency-element"></xref></td> target="samplingfrequency-element"/></td>
</tr>

<tr>
<td align="right">0xB6</td>
<td align="left">ChapterAtom</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapteratom-element"></xref></td> target="chapteratom-element"/></td>
</tr>

<tr>
<td align="right">0xB7</td>
<td align="left">CueTrackPositions</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cuetrackpositions-element"></xref></td> target="cuetrackpositions-element"/></td>
</tr>

<tr>
<td align="right">0xB9</td>
<td align="left">FlagEnabled</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flagenabled-element"></xref></td> target="flagenabled-element"/></td>
</tr>

<tr>
<td align="right">0xBA</td>
<td align="left">PixelHeight</td>
<td align="left">Described in align="left">RFC 9559, <xref target="pixelheight-element"></xref></td> target="pixelheight-element"/></td>
</tr>

<tr>
<td align="right">0xBB</td>
<td align="left">CuePoint</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cuepoint-element"></xref></td> target="cuepoint-element"/></td>
</tr>

<tr>
<td align="right">0xC0</td>
<td align="left">TrickTrackUID</td>
<td align="left">Reclaimed (<xref target="tricktrackuid-element"></xref>)</td> (RFC 9559, <xref target="tricktrackuid-element"/>)</td>
</tr>

<tr>
<td align="right">0xC1</td>
<td align="left">TrickTrackSegmentUID</td>
<td align="left">Reclaimed (<xref target="tricktracksegmentuid-element"></xref>)</td> (RFC 9559, <xref target="tricktracksegmentuid-element"/>)</td>
</tr>

<tr>
<td align="right">0xC4</td>
<td align="left">TrickMasterTrackSegmentUID</td>
<td align="left">Reclaimed (<xref target="trickmastertracksegmentuid-element"></xref>)</td> (RFC 9559, <xref target="trickmastertracksegmentuid-element"/>)</td>
</tr>

<tr>
<td align="right">0xC6</td>
<td align="left">TrickTrackFlag</td>
<td align="left">Reclaimed (<xref target="tricktrackflag-element"></xref>)</td> (RFC 9559, <xref target="tricktrackflag-element"/>)</td>
</tr>

<tr>
<td align="right">0xC7</td>
<td align="left">TrickMasterTrackUID</td>
<td align="left">Reclaimed (<xref target="trickmastertrackuid-element"></xref>)</td> (RFC 9559, <xref target="trickmastertrackuid-element"/>)</td>
</tr>

<tr>
<td align="right">0xC8</td>
<td align="left">ReferenceFrame</td>
<td align="left">Reclaimed (<xref target="referenceframe-element"></xref>)</td> (RFC 9559, <xref target="referenceframe-element"/>)</td>
</tr>

<tr>
<td align="right">0xC9</td>
<td align="left">ReferenceOffset</td>
<td align="left">Reclaimed (<xref target="referenceoffset-element"></xref>)</td> (RFC 9559, <xref target="referenceoffset-element"/>)</td>
</tr>

<tr>
<td align="right">0xCA</td>
<td align="left">ReferenceTimestamp</td>
<td align="left">Reclaimed (<xref target="referencetimestamp-element"></xref>)</td> (RFC 9559, <xref target="referencetimestamp-element"/>)</td>
</tr>

<tr>
<td align="right">0xCB</td>
<td align="left">BlockAdditionID</td>
<td align="left">Reclaimed (<xref target="blockadditionid-element"></xref>)</td> (RFC 9559, <xref target="blockadditionid-element"/>)</td>
</tr>

<tr>
<td align="right">0xCC</td>
<td align="left">LaceNumber</td>
<td align="left">Reclaimed (<xref target="lacenumber-element"></xref>)</td> (RFC 9559, <xref target="lacenumber-element"/>)</td>
</tr>

<tr>
<td align="right">0xCD</td>
<td align="left">FrameNumber</td>
<td align="left">Reclaimed (<xref target="framenumber-element"></xref>)</td> (RFC 9559, <xref target="framenumber-element"/>)</td>
</tr>

<tr>
<td align="right">0xCE</td>
<td align="left">Delay</td>
<td align="left">Reclaimed (<xref target="delay-element"></xref>)</td> (RFC 9559, <xref target="delay-element"/>)</td>
</tr>

<tr>
<td align="right">0xCF</td>
<td align="left">SliceDuration</td>
<td align="left">Reclaimed (<xref target="sliceduration-element"></xref>)</td> (RFC 9559, <xref target="sliceduration-element"/>)</td>
</tr>

<tr>
<td align="right">0xD7</td>
<td align="left">TrackNumber</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tracknumber-element"></xref></td> target="tracknumber-element"/></td>
</tr>

<tr>
<td align="right">0xDB</td>
<td align="left">CueReference</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cuereference-element"></xref></td> target="cuereference-element"/></td>
</tr>

<tr>
<td align="right">0xE0</td>
<td align="left">Video</td>
<td align="left">Described in align="left">RFC 9559, <xref target="video-element"></xref></td> target="video-element"/></td>
</tr>

<tr>
<td align="right">0xE1</td>
<td align="left">Audio</td>
<td align="left">Described in align="left">RFC 9559, <xref target="audio-element"></xref></td> target="audio-element"/></td>
</tr>

<tr>
<td align="right">0xE2</td>
<td align="left">TrackOperation</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackoperation-element"></xref></td> target="trackoperation-element"/></td>
</tr>

<tr>
<td align="right">0xE3</td>
<td align="left">TrackCombinePlanes</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackcombineplanes-element"></xref></td> target="trackcombineplanes-element"/></td>
</tr>

<tr>
<td align="right">0xE4</td>
<td align="left">TrackPlane</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackplane-element"></xref></td> target="trackplane-element"/></td>
</tr>

<tr>
<td align="right">0xE5</td>
<td align="left">TrackPlaneUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackplaneuid-element"></xref></td> target="trackplaneuid-element"/></td>
</tr>

<tr>
<td align="right">0xE6</td>
<td align="left">TrackPlaneType</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackplanetype-element"></xref></td> target="trackplanetype-element"/></td>
</tr>

<tr>
<td align="right">0xE7</td>
<td align="left">Timestamp</td>
<td align="left">Described in align="left">RFC 9559, <xref target="timestamp-element"></xref></td> target="timestamp-element"/></td>
</tr>

<tr>
<td align="right">0xE8</td>
<td align="left">TimeSlice</td>
<td align="left">Reclaimed (<xref target="timeslice-element"></xref>)</td> (RFC 9559, <xref target="timeslice-element"/>)</td>
</tr>

<tr>
<td align="right">0xE9</td>
<td align="left">TrackJoinBlocks</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackjoinblocks-element"></xref></td> target="trackjoinblocks-element"/></td>
</tr>

<tr>
<td align="right">0xEA</td>
<td align="left">CueCodecState</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cuecodecstate-element"></xref></td> target="cuecodecstate-element"/></td>
</tr>

<tr>
<td align="right">0xEB</td>
<td align="left">CueRefCodecState</td>
<td align="left">Reclaimed (<xref target="cuerefcodecstate-element"></xref>)</td> (RFC 9559, <xref target="cuerefcodecstate-element"/>)</td>
</tr>

<tr>
<td align="right">0xED</td>
<td align="left">TrackJoinUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackjoinuid-element"></xref></td> target="trackjoinuid-element"/></td>
</tr>

<tr>
<td align="right">0xEE</td>
<td align="left">BlockAddID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockaddid-element"></xref></td> target="blockaddid-element"/></td>
</tr>

<tr>
<td align="right">0xF0</td>
<td align="left">CueRelativePosition</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cuerelativeposition-element"></xref></td> target="cuerelativeposition-element"/></td>
</tr>

<tr>
<td align="right">0xF1</td>
<td align="left">CueClusterPosition</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cueclusterposition-element"></xref></td> target="cueclusterposition-element"/></td>
</tr>

<tr>
<td align="right">0xF7</td>
<td align="left">CueTrack</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cuetrack-element"></xref></td> target="cuetrack-element"/></td>
</tr>

<tr>
<td align="right">0xFA</td>
<td align="left">ReferencePriority</td>
<td align="left">Described in align="left">RFC 9559, <xref target="referencepriority-element"></xref></td> target="referencepriority-element"/></td>
</tr>

<tr>
<td align="right">0xFB</td>
<td align="left">ReferenceBlock</td>
<td align="left">Described in align="left">RFC 9559, <xref target="referenceblock-element"></xref></td> target="referenceblock-element"/></td>
</tr>

<tr>
<td align="right">0xFD</td>
<td align="left">ReferenceVirtual</td>
<td align="left">Reclaimed (<xref target="referencevirtual-element"></xref>)</td> (RFC 9559, <xref target="referencevirtual-element"/>)</td>
</tr>

<tr>
<td align="right">0xFF</td>
<td align="left">Reserved</td>
<td align="left">RFC 9559</td>
</tr>
<tr>
<td align="right">0x0100-0x407E</td>
<td align="left">Not valid for use as an Element ID</td>
<td align="left">RFC 9559, <xref target="matroska-element-ids-registry"/></td>
</tr>

<tr>
<td align="right">0x41A4</td>
<td align="left">BlockAddIDName</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockaddidname-element"></xref></td> target="blockaddidname-element"/></td>
</tr>

<tr>
<td align="right">0x41E4</td>
<td align="left">BlockAdditionMapping</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockadditionmapping-element"></xref></td> target="blockadditionmapping-element"/></td>
</tr>

<tr>
<td align="right">0x41E7</td>
<td align="left">BlockAddIDType</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockaddidtype-element"></xref></td> target="blockaddidtype-element"/></td>
</tr>

<tr>
<td align="right">0x41ED</td>
<td align="left">BlockAddIDExtraData</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockaddidextradata-element"></xref></td> target="blockaddidextradata-element"/></td>
</tr>

<tr>
<td align="right">0x41F0</td>
<td align="left">BlockAddIDValue</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockaddidvalue-element"></xref></td> target="blockaddidvalue-element"/></td>
</tr>

<tr>
<td align="right">0x4254</td>
<td align="left">ContentCompAlgo</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentcompalgo-element"></xref></td> target="contentcompalgo-element"/></td>
</tr>

<tr>
<td align="right">0x4255</td>
<td align="left">ContentCompSettings</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentcompsettings-element"></xref></td> target="contentcompsettings-element"/></td>
</tr>

<tr>
<td align="right">0x437C</td>
<td align="left">ChapLanguage</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaplanguage-element"></xref></td> target="chaplanguage-element"/></td>
</tr>

<tr>
<td align="right">0x437D</td>
<td align="left">ChapLanguageBCP47</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaplanguagebcp47-element"></xref></td> target="chaplanguagebcp47-element"/></td>
</tr>

<tr>
<td align="right">0x437E</td>
<td align="left">ChapCountry</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapcountry-element"></xref></td> target="chapcountry-element"/></td>
</tr>

<tr>
<td align="right">0x4444</td>
<td align="left">SegmentFamily</td>
<td align="left">Described in align="left">RFC 9559, <xref target="segmentfamily-element"></xref></td> target="segmentfamily-element"/></td>
</tr>

<tr>
<td align="right">0x4461</td>
<td align="left">DateUTC</td>
<td align="left">Described in align="left">RFC 9559, <xref target="dateutc-element"></xref></td> target="dateutc-element"/></td>
</tr>

<tr>
<td align="right">0x447A</td>
<td align="left">TagLanguage</td>
<td align="left">Described in align="left">RFC 9559, <xref target="taglanguage-element"></xref></td> target="taglanguage-element"/></td>
</tr>

<tr>
<td align="right">0x447B</td>
<td align="left">TagLanguageBCP47</td>
<td align="left">Described in align="left">RFC 9559, <xref target="taglanguagebcp47-element"></xref></td> target="taglanguagebcp47-element"/></td>
</tr>

<tr>
<td align="right">0x4484</td>
<td align="left">TagDefault</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tagdefault-element"></xref></td> target="tagdefault-element"/></td>
</tr>

<tr>
<td align="right">0x4485</td>
<td align="left">TagBinary</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tagbinary-element"></xref></td> target="tagbinary-element"/></td>
</tr>

<tr>
<td align="right">0x4487</td>
<td align="left">TagString</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tagstring-element"></xref></td> target="tagstring-element"/></td>
</tr>

<tr>
<td align="right">0x4489</td>
<td align="left">Duration</td>
<td align="left">Described in align="left">RFC 9559, <xref target="duration-element"></xref></td> target="duration-element"/></td>
</tr>

<tr>
<td align="right">0x44B4</td>
<td align="left">TagDefaultBogus</td>
<td align="left">Reclaimed (<xref target="tagdefaultbogus-element"></xref>)</td> (RFC 9559, <xref target="tagdefaultbogus-element"/>)</td>
</tr>

<tr>
<td align="right">0x450D</td>
<td align="left">ChapProcessPrivate</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapprocessprivate-element"></xref></td> target="chapprocessprivate-element"/></td>
</tr>

<tr>
<td align="right">0x45A3</td>
<td align="left">TagName</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tagname-element"></xref></td> target="tagname-element"/></td>
</tr>

<tr>
<td align="right">0x45B9</td>
<td align="left">EditionEntry</td>
<td align="left">Described in align="left">RFC 9559, <xref target="editionentry-element"></xref></td> target="editionentry-element"/></td>
</tr>

<tr>
<td align="right">0x45BC</td>
<td align="left">EditionUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="editionuid-element"></xref></td> target="editionuid-element"/></td>
</tr>

<tr>
<td align="right">0x45DB</td>
<td align="left">EditionFlagDefault</td>
<td align="left">Described in align="left">RFC 9559, <xref target="editionflagdefault-element"></xref></td> target="editionflagdefault-element"/></td>
</tr>

<tr>
<td align="right">0x45DD</td>
<td align="left">EditionFlagOrdered</td>
<td align="left">Described in align="left">RFC 9559, <xref target="editionflagordered-element"></xref></td> target="editionflagordered-element"/></td>
</tr>

<tr>
<td align="right">0x465C</td>
<td align="left">FileData</td>
<td align="left">Described in align="left">RFC 9559, <xref target="filedata-element"></xref></td> target="filedata-element"/></td>
</tr>

<tr>
<td align="right">0x4660</td>
<td align="left">FileMediaType</td>
<td align="left">Described in align="left">RFC 9559, <xref target="filemediatype-element"></xref></td> target="filemediatype-element"/></td>
</tr>

<tr>
<td align="right">0x4661</td>
<td align="left">FileUsedStartTime</td>
<td align="left">Reclaimed (<xref target="fileusedstarttime-element"></xref>)</td> (RFC 9559, <xref target="fileusedstarttime-element"/>)</td>
</tr>

<tr>
<td align="right">0x4662</td>
<td align="left">FileUsedEndTime</td>
<td align="left">Reclaimed (<xref target="fileusedendtime-element"></xref>)</td> (RFC 9559, <xref target="fileusedendtime-element"/>)</td>
</tr>

<tr>
<td align="right">0x466E</td>
<td align="left">FileName</td>
<td align="left">Described in align="left">RFC 9559, <xref target="filename-element"></xref></td> target="filename-element"/></td>
</tr>

<tr>
<td align="right">0x4675</td>
<td align="left">FileReferral</td>
<td align="left">Reclaimed (<xref target="filereferral-element"></xref>)</td> (RFC 9559, <xref target="filereferral-element"/>)</td>
</tr>

<tr>
<td align="right">0x467E</td>
<td align="left">FileDescription</td>
<td align="left">Described in align="left">RFC 9559, <xref target="filedescription-element"></xref></td> target="filedescription-element"/></td>
</tr>

<tr>
<td align="right">0x46AE</td>
<td align="left">FileUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="fileuid-element"></xref></td> target="fileuid-element"/></td>
</tr>

<tr>
<td align="right">0x47E1</td>
<td align="left">ContentEncAlgo</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentencalgo-element"></xref></td> target="contentencalgo-element"/></td>
</tr>

<tr>
<td align="right">0x47E2</td>
<td align="left">ContentEncKeyID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentenckeyid-element"></xref></td> target="contentenckeyid-element"/></td>
</tr>

<tr>
<td align="right">0x47E3</td>
<td align="left">ContentSignature</td>
<td align="left">Reclaimed (<xref target="contentsignature-element"></xref>)</td> (RFC 9559, <xref target="contentsignature-element"/>)</td>
</tr>

<tr>
<td align="right">0x47E4</td>
<td align="left">ContentSigKeyID</td>
<td align="left">Reclaimed (<xref target="contentsigkeyid-element"></xref>)</td> (RFC 9559, <xref target="contentsigkeyid-element"/>)</td>
</tr>

<tr>
<td align="right">0x47E5</td>
<td align="left">ContentSigAlgo</td>
<td align="left">Reclaimed (<xref target="contentsigalgo-element"></xref>)</td> (RFC 9559, <xref target="contentsigalgo-element"/>)</td>
</tr>

<tr>
<td align="right">0x47E6</td>
<td align="left">ContentSigHashAlgo</td>
<td align="left">Reclaimed (<xref target="contentsighashalgo-element"></xref>)</td> (RFC 9559, <xref target="contentsighashalgo-element"/>)</td>
</tr>

<tr>
<td align="right">0x47E7</td>
<td align="left">ContentEncAESSettings</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentencaessettings-element"></xref></td> target="contentencaessettings-element"/></td>
</tr>

<tr>
<td align="right">0x47E8</td>
<td align="left">AESSettingsCipherMode</td>
<td align="left">Described in align="left">RFC 9559, <xref target="aessettingsciphermode-element"></xref></td> target="aessettingsciphermode-element"/></td>
</tr>

<tr>
<td align="right">0x4D80</td>
<td align="left">MuxingApp</td>
<td align="left">Described in align="left">RFC 9559, <xref target="muxingapp-element"></xref></td> target="muxingapp-element"/></td>
</tr>

<tr>
<td align="right">0x4DBB</td>
<td align="left">Seek</td>
<td align="left">Described in align="left">RFC 9559, <xref target="seek-element"></xref></td> target="seek-element"/></td>
</tr>

<tr>
<td align="right">0x5031</td>
<td align="left">ContentEncodingOrder</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentencodingorder-element"></xref></td> target="contentencodingorder-element"/></td>
</tr>

<tr>
<td align="right">0x5032</td>
<td align="left">ContentEncodingScope</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentencodingscope-element"></xref></td> target="contentencodingscope-element"/></td>
</tr>

<tr>
<td align="right">0x5033</td>
<td align="left">ContentEncodingType</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentencodingtype-element"></xref></td> target="contentencodingtype-element"/></td>
</tr>

<tr>
<td align="right">0x5034</td>
<td align="left">ContentCompression</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentcompression-element"></xref></td> target="contentcompression-element"/></td>
</tr>

<tr>
<td align="right">0x5035</td>
<td align="left">ContentEncryption</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentencryption-element"></xref></td> target="contentencryption-element"/></td>
</tr>

<tr>
<td align="right">0x535F</td>
<td align="left">CueRefNumber</td>
<td align="left">Reclaimed (<xref target="cuerefnumber-element"></xref>)</td> (RFC 9559, <xref target="cuerefnumber-element"/>)</td>
</tr>

<tr>
<td align="right">0x536E</td>
<td align="left">Name</td>
<td align="left">Described in align="left">RFC 9559, <xref target="name-element"></xref></td> target="name-element"/></td>
</tr>

<tr>
<td align="right">0x5378</td>
<td align="left">CueBlockNumber</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cueblocknumber-element"></xref></td> target="cueblocknumber-element"/></td>
</tr>

<tr>
<td align="right">0x537F</td>
<td align="left">TrackOffset</td>
<td align="left">Reclaimed (<xref target="trackoffset-element"></xref>)</td> (RFC 9559, <xref target="trackoffset-element"/>)</td>
</tr>

<tr>
<td align="right">0x53AB</td>
<td align="left">SeekID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="seekid-element"></xref></td> target="seekid-element"/></td>
</tr>

<tr>
<td align="right">0x53AC</td>
<td align="left">SeekPosition</td>
<td align="left">Described in align="left">RFC 9559, <xref target="seekposition-element"></xref></td> target="seekposition-element"/></td>
</tr>

<tr>
<td align="right">0x53B8</td>
<td align="left">StereoMode</td>
<td align="left">Described in align="left">RFC 9559, <xref target="stereomode-element"></xref></td> target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">0x53B9</td>
<td align="left">OldStereoMode</td>
<td align="left">Described in align="left">RFC 9559, <xref target="oldstereomode-element"></xref></td> target="oldstereomode-element"/></td>
</tr>

<tr>
<td align="right">0x53C0</td>
<td align="left">AlphaMode</td>
<td align="left">Described in align="left">RFC 9559, <xref target="alphamode-element"></xref></td> target="alphamode-element"/></td>
</tr>

<tr>
<td align="right">0x54AA</td>
<td align="left">PixelCropBottom</td>
<td align="left">Described in align="left">RFC 9559, <xref target="pixelcropbottom-element"></xref></td> target="pixelcropbottom-element"/></td>
</tr>

<tr>
<td align="right">0x54B0</td>
<td align="left">DisplayWidth</td>
<td align="left">Described in align="left">RFC 9559, <xref target="displaywidth-element"></xref></td> target="displaywidth-element"/></td>
</tr>

<tr>
<td align="right">0x54B2</td>
<td align="left">DisplayUnit</td>
<td align="left">Described in align="left">RFC 9559, <xref target="displayunit-element"></xref></td> target="displayunit-element"/></td>
</tr>

<tr>
<td align="right">0x54B3</td>
<td align="left">AspectRatioType</td>
<td align="left">Reclaimed (<xref target="aspectratiotype-element"></xref>)</td> (RFC 9559, <xref target="aspectratiotype-element"/>)</td>
</tr>

<tr>
<td align="right">0x54BA</td>
<td align="left">DisplayHeight</td>
<td align="left">Described in align="left">RFC 9559, <xref target="displayheight-element"></xref></td> target="displayheight-element"/></td>
</tr>

<tr>
<td align="right">0x54BB</td>
<td align="left">PixelCropTop</td>
<td align="left">Described in align="left">RFC 9559, <xref target="pixelcroptop-element"></xref></td> target="pixelcroptop-element"/></td>
</tr>

<tr>
<td align="right">0x54CC</td>
<td align="left">PixelCropLeft</td>
<td align="left">Described in align="left">RFC 9559, <xref target="pixelcropleft-element"></xref></td> target="pixelcropleft-element"/></td>
</tr>

<tr>
<td align="right">0x54DD</td>
<td align="left">PixelCropRight</td>
<td align="left">Described in align="left">RFC 9559, <xref target="pixelcropright-element"></xref></td> target="pixelcropright-element"/></td>
</tr>

<tr>
<td align="right">0x55AA</td>
<td align="left">FlagForced</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flagforced-element"></xref></td> target="flagforced-element"/></td>
</tr>

<tr>
<td align="right">0x55AB</td>
<td align="left">FlagHearingImpaired</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flaghearingimpaired-element"></xref></td> target="flaghearingimpaired-element"/></td>
</tr>

<tr>
<td align="right">0x55AC</td>
<td align="left">FlagVisualImpaired</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flagvisualimpaired-element"></xref></td> target="flagvisualimpaired-element"/></td>
</tr>

<tr>
<td align="right">0x55AD</td>
<td align="left">FlagTextDescriptions</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flagtextdescriptions-element"></xref></td> target="flagtextdescriptions-element"/></td>
</tr>

<tr>
<td align="right">0x55AE</td>
<td align="left">FlagOriginal</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flagoriginal-element"></xref></td> target="flagoriginal-element"/></td>
</tr>

<tr>
<td align="right">0x55AF</td>
<td align="left">FlagCommentary</td>
<td align="left">Described in align="left">RFC 9559, <xref target="flagcommentary-element"></xref></td> target="flagcommentary-element"/></td>
</tr>

<tr>
<td align="right">0x55B0</td>
<td align="left">Colour</td>
<td align="left">Described in align="left">RFC 9559, <xref target="colour-element"></xref></td> target="colour-element"/></td>
</tr>

<tr>
<td align="right">0x55B1</td>
<td align="left">MatrixCoefficients</td>
<td align="left">Described in align="left">RFC 9559, <xref target="matrixcoefficients-element"></xref></td> target="matrixcoefficients-element"/></td>
</tr>

<tr>
<td align="right">0x55B2</td>
<td align="left">BitsPerChannel</td>
<td align="left">Described in align="left">RFC 9559, <xref target="bitsperchannel-element"></xref></td> target="bitsperchannel-element"/></td>
</tr>

<tr>
<td align="right">0x55B3</td>
<td align="left">ChromaSubsamplingHorz</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chromasubsamplinghorz-element"></xref></td> target="chromasubsamplinghorz-element"/></td>
</tr>

<tr>
<td align="right">0x55B4</td>
<td align="left">ChromaSubsamplingVert</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chromasubsamplingvert-element"></xref></td> target="chromasubsamplingvert-element"/></td>
</tr>

<tr>
<td align="right">0x55B5</td>
<td align="left">CbSubsamplingHorz</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cbsubsamplinghorz-element"></xref></td> target="cbsubsamplinghorz-element"/></td>
</tr>

<tr>
<td align="right">0x55B6</td>
<td align="left">CbSubsamplingVert</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cbsubsamplingvert-element"></xref></td> target="cbsubsamplingvert-element"/></td>
</tr>

<tr>
<td align="right">0x55B7</td>
<td align="left">ChromaSitingHorz</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chromasitinghorz-element"></xref></td> target="chromasitinghorz-element"/></td>
</tr>

<tr>
<td align="right">0x55B8</td>
<td align="left">ChromaSitingVert</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chromasitingvert-element"></xref></td> target="chromasitingvert-element"/></td>
</tr>

<tr>
<td align="right">0x55B9</td>
<td align="left">Range</td>
<td align="left">Described in align="left">RFC 9559, <xref target="range-element"></xref></td> target="color-range-element"/></td>
</tr>

<tr>
<td align="right">0x55BA</td>
<td align="left">TransferCharacteristics</td>
<td align="left">Described in align="left">RFC 9559, <xref target="transfercharacteristics-element"></xref></td> target="transfercharacteristics-element"/></td>
</tr>

<tr>
<td align="right">0x55BB</td>
<td align="left">Primaries</td>
<td align="left">Described in align="left">RFC 9559, <xref target="primaries-element"></xref></td> target="primaries-element"/></td>
</tr>

<tr>
<td align="right">0x55BC</td>
<td align="left">MaxCLL</td>
<td align="left">Described in align="left">RFC 9559, <xref target="maxcll-element"></xref></td> target="maxcll-element"/></td>
</tr>

<tr>
<td align="right">0x55BD</td>
<td align="left">MaxFALL</td>
<td align="left">Described in align="left">RFC 9559, <xref target="maxfall-element"></xref></td> target="maxfall-element"/></td>
</tr>

<tr>
<td align="right">0x55D0</td>
<td align="left">MasteringMetadata</td>
<td align="left">Described in align="left">RFC 9559, <xref target="masteringmetadata-element"></xref></td> target="masteringmetadata-element"/></td>
</tr>

<tr>
<td align="right">0x55D1</td>
<td align="left">PrimaryRChromaticityX</td>
<td align="left">Described in align="left">RFC 9559, <xref target="primaryrchromaticityx-element"></xref></td> target="primaryrchromaticityx-element"/></td>
</tr>

<tr>
<td align="right">0x55D2</td>
<td align="left">PrimaryRChromaticityY</td>
<td align="left">Described in align="left">RFC 9559, <xref target="primaryrchromaticityy-element"></xref></td> target="primaryrchromaticityy-element"/></td>
</tr>

<tr>
<td align="right">0x55D3</td>
<td align="left">PrimaryGChromaticityX</td>
<td align="left">Described in align="left">RFC 9559, <xref target="primarygchromaticityx-element"></xref></td> target="primarygchromaticityx-element"/></td>
</tr>

<tr>
<td align="right">0x55D4</td>
<td align="left">PrimaryGChromaticityY</td>
<td align="left">Described in align="left">RFC 9559, <xref target="primarygchromaticityy-element"></xref></td> target="primarygchromaticityy-element"/></td>
</tr>

<tr>
<td align="right">0x55D5</td>
<td align="left">PrimaryBChromaticityX</td>
<td align="left">Described in align="left">RFC 9559, <xref target="primarybchromaticityx-element"></xref></td> target="primarybchromaticityx-element"/></td>
</tr>

<tr>
<td align="right">0x55D6</td>
<td align="left">PrimaryBChromaticityY</td>
<td align="left">Described in align="left">RFC 9559, <xref target="primarybchromaticityy-element"></xref></td> target="primarybchromaticityy-element"/></td>
</tr>

<tr>
<td align="right">0x55D7</td>
<td align="left">WhitePointChromaticityX</td>
<td align="left">Described in align="left">RFC 9559, <xref target="whitepointchromaticityx-element"></xref></td> target="whitepointchromaticityx-element"/></td>
</tr>

<tr>
<td align="right">0x55D8</td>
<td align="left">WhitePointChromaticityY</td>
<td align="left">Described in align="left">RFC 9559, <xref target="whitepointchromaticityy-element"></xref></td> target="whitepointchromaticityy-element"/></td>
</tr>

<tr>
<td align="right">0x55D9</td>
<td align="left">LuminanceMax</td>
<td align="left">Described in align="left">RFC 9559, <xref target="luminancemax-element"></xref></td> target="luminancemax-element"/></td>
</tr>

<tr>
<td align="right">0x55DA</td>
<td align="left">LuminanceMin</td>
<td align="left">Described in align="left">RFC 9559, <xref target="luminancemin-element"></xref></td> target="luminancemin-element"/></td>
</tr>

<tr>
<td align="right">0x55EE</td>
<td align="left">MaxBlockAdditionID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="maxblockadditionid-element"></xref></td> target="maxblockadditionid-element"/></td>
</tr>

<tr>
<td align="right">0x5654</td>
<td align="left">ChapterStringUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapterstringuid-element"></xref></td> target="chapterstringuid-element"/></td>
</tr>

<tr>
<td align="right">0x56AA</td>
<td align="left">CodecDelay</td>
<td align="left">Described in align="left">RFC 9559, <xref target="codecdelay-element"></xref></td> target="codecdelay-element"/></td>
</tr>

<tr>
<td align="right">0x56BB</td>
<td align="left">SeekPreRoll</td>
<td align="left">Described in align="left">RFC 9559, <xref target="seekpreroll-element"></xref></td> target="seekpreroll-element"/></td>
</tr>

<tr>
<td align="right">0x5741</td>
<td align="left">WritingApp</td>
<td align="left">Described in align="left">RFC 9559, <xref target="writingapp-element"></xref></td> target="writingapp-element"/></td>
</tr>

<tr>
<td align="right">0x5854</td>
<td align="left">SilentTracks</td>
<td align="left">Reclaimed (<xref target="silenttracks-element"></xref>)</td> (RFC 9559, <xref target="silenttracks-element"/>)</td>
</tr>

<tr>
<td align="right">0x58D7</td>
<td align="left">SilentTrackNumber</td>
<td align="left">Reclaimed (<xref target="silenttracknumber-element"></xref>)</td> (RFC 9559, <xref target="silenttracknumber-element"/>)</td>
</tr>

<tr>
<td align="right">0x61A7</td>
<td align="left">AttachedFile</td>
<td align="left">Described in align="left">RFC 9559, <xref target="attachedfile-element"></xref></td> target="attachedfile-element"/></td>
</tr>

<tr>
<td align="right">0x6240</td>
<td align="left">ContentEncoding</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentencoding-element"></xref></td> target="contentencoding-element"/></td>
</tr>

<tr>
<td align="right">0x6264</td>
<td align="left">BitDepth</td>
<td align="left">Described in align="left">RFC 9559, <xref target="bitdepth-element"></xref></td> target="bitdepth-element"/></td>
</tr>

<tr>
<td align="right">0x63A2</td>
<td align="left">CodecPrivate</td>
<td align="left">Described in align="left">RFC 9559, <xref target="codecprivate-element"></xref></td> target="codecprivate-element"/></td>
</tr>

<tr>
<td align="right">0x63C0</td>
<td align="left">Targets</td>
<td align="left">Described in align="left">RFC 9559, <xref target="targets-element"></xref></td> target="targets-element"/></td>
</tr>

<tr>
<td align="right">0x63C3</td>
<td align="left">ChapterPhysicalEquiv</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapterphysicalequiv-element"></xref></td> target="chapterphysicalequiv-element"/></td>
</tr>

<tr>
<td align="right">0x63C4</td>
<td align="left">TagChapterUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tagchapteruid-element"></xref></td> target="tagchapteruid-element"/></td>
</tr>

<tr>
<td align="right">0x63C5</td>
<td align="left">TagTrackUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tagtrackuid-element"></xref></td> target="tagtrackuid-element"/></td>
</tr>

<tr>
<td align="right">0x63C6</td>
<td align="left">TagAttachmentUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tagattachmentuid-element"></xref></td> target="tagattachmentuid-element"/></td>
</tr>

<tr>
<td align="right">0x63C9</td>
<td align="left">TagEditionUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tageditionuid-element"></xref></td> target="tageditionuid-element"/></td>
</tr>

<tr>
<td align="right">0x63CA</td>
<td align="left">TargetType</td>
<td align="left">Described in align="left">RFC 9559, <xref target="targettype-element"></xref></td> target="targettype-element"/></td>
</tr>

<tr>
<td align="right">0x6624</td>
<td align="left">TrackTranslate</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tracktranslate-element"></xref></td> target="tracktranslate-element"/></td>
</tr>

<tr>
<td align="right">0x66A5</td>
<td align="left">TrackTranslateTrackID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tracktranslatetrackid-element"></xref></td> target="tracktranslatetrackid-element"/></td>
</tr>

<tr>
<td align="right">0x66BF</td>
<td align="left">TrackTranslateCodec</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tracktranslatecodec-element"></xref></td> target="tracktranslatecodec-element"/></td>
</tr>

<tr>
<td align="right">0x66FC</td>
<td align="left">TrackTranslateEditionUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tracktranslateeditionuid-element"></xref></td> target="tracktranslateeditionuid-element"/></td>
</tr>

<tr>
<td align="right">0x67C8</td>
<td align="left">SimpleTag</td>
<td align="left">Described in align="left">RFC 9559, <xref target="simpletag-element"></xref></td> target="simpletag-element"/></td>
</tr>

<tr>
<td align="right">0x68CA</td>
<td align="left">TargetTypeValue</td>
<td align="left">Described in align="left">RFC 9559, <xref target="targettypevalue-element"></xref></td> target="targettypevalue-element"/></td>
</tr>

<tr>
<td align="right">0x6911</td>
<td align="left">ChapProcessCommand</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapprocesscommand-element"></xref></td> target="chapprocesscommand-element"/></td>
</tr>

<tr>
<td align="right">0x6922</td>
<td align="left">ChapProcessTime</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapprocesstime-element"></xref></td> target="chapprocesstime-element"/></td>
</tr>

<tr>
<td align="right">0x6924</td>
<td align="left">ChapterTranslate</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaptertranslate-element"></xref></td> target="chaptertranslate-element"/></td>
</tr>

<tr>
<td align="right">0x6933</td>
<td align="left">ChapProcessData</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapprocessdata-element"></xref></td> target="chapprocessdata-element"/></td>
</tr>

<tr>
<td align="right">0x6944</td>
<td align="left">ChapProcess</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapprocess-element"></xref></td> target="chapprocess-element"/></td>
</tr>

<tr>
<td align="right">0x6955</td>
<td align="left">ChapProcessCodecID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapprocesscodecid-element"></xref></td> target="chapprocesscodecid-element"/></td>
</tr>

<tr>
<td align="right">0x69A5</td>
<td align="left">ChapterTranslateID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaptertranslateid-element"></xref></td> target="chaptertranslateid-element"/></td>
</tr>

<tr>
<td align="right">0x69BF</td>
<td align="left">ChapterTranslateCodec</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaptertranslatecodec-element"></xref></td> target="chaptertranslatecodec-element"/></td>
</tr>

<tr>
<td align="right">0x69FC</td>
<td align="left">ChapterTranslateEditionUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaptertranslateeditionuid-element"></xref></td> target="chaptertranslateeditionuid-element"/></td>
</tr>

<tr>
<td align="right">0x6D80</td>
<td align="left">ContentEncodings</td>
<td align="left">Described in align="left">RFC 9559, <xref target="contentencodings-element"></xref></td> target="contentencodings-element"/></td>
</tr>

<tr>
<td align="right">0x6DE7</td>
<td align="left">MinCache</td>
<td align="left">Reclaimed (<xref target="mincache-element"></xref>)</td> (RFC 9559, <xref target="mincache-element"/>)</td>
</tr>

<tr>
<td align="right">0x6DF8</td>
<td align="left">MaxCache</td>
<td align="left">Reclaimed (<xref target="maxcache-element"></xref>)</td> (RFC 9559, <xref target="maxcache-element"/>)</td>
</tr>

<tr>
<td align="right">0x6E67</td>
<td align="left">ChapterSegmentUUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaptersegmentuuid-element"></xref></td> target="chaptersegmentuuid-element"/></td>
</tr>

<tr>
<td align="right">0x6EBC</td>
<td align="left">ChapterSegmentEditionUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chaptersegmenteditionuid-element"></xref></td> target="chaptersegmenteditionuid-element"/></td>
</tr>

<tr>
<td align="right">0x6FAB</td>
<td align="left">TrackOverlay</td>
<td align="left">Reclaimed (<xref target="trackoverlay-element"></xref>)</td> (RFC 9559, <xref target="trackoverlay-element"/>)</td>
</tr>

<tr>
<td align="right">0x7373</td>
<td align="left">Tag</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tag-element"></xref></td> target="tag-element"/></td>
</tr>

<tr>
<td align="right">0x7384</td>
<td align="left">SegmentFilename</td>
<td align="left">Described in align="left">RFC 9559, <xref target="segmentfilename-element"></xref></td> target="segmentfilename-element"/></td>
</tr>

<tr>
<td align="right">0x73A4</td>
<td align="left">SegmentUUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="segmentuuid-element"></xref></td> target="segmentuuid-element"/></td>
</tr>

<tr>
<td align="right">0x73C4</td>
<td align="left">ChapterUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapteruid-element"></xref></td> target="chapteruid-element"/></td>
</tr>

<tr>
<td align="right">0x73C5</td>
<td align="left">TrackUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="trackuid-element"></xref></td> target="trackuid-element"/></td>
</tr>

<tr>
<td align="right">0x7446</td>
<td align="left">AttachmentLink</td>
<td align="left">Described in align="left">RFC 9559, <xref target="attachmentlink-element"></xref></td> target="attachmentlink-element"/></td>
</tr>

<tr>
<td align="right">0x75A1</td>
<td align="left">BlockAdditions</td>
<td align="left">Described in align="left">RFC 9559, <xref target="blockadditions-element"></xref></td> target="blockadditions-element"/></td>
</tr>

<tr>
<td align="right">0x75A2</td>
<td align="left">DiscardPadding</td>
<td align="left">Described in align="left">RFC 9559, <xref target="discardpadding-element"></xref></td> target="discardpadding-element"/></td>
</tr>

<tr>
<td align="right">0x7670</td>
<td align="left">Projection</td>
<td align="left">Described in align="left">RFC 9559, <xref target="projection-element"></xref></td> target="projection-element"/></td>
</tr>

<tr>
<td align="right">0x7671</td>
<td align="left">ProjectionType</td>
<td align="left">Described in align="left">RFC 9559, <xref target="projectiontype-element"></xref></td> target="projectiontype-element"/></td>
</tr>

<tr>
<td align="right">0x7672</td>
<td align="left">ProjectionPrivate</td>
<td align="left">Described in align="left">RFC 9559, <xref target="projectionprivate-element"></xref></td> target="projectionprivate-element"/></td>
</tr>

<tr>
<td align="right">0x7673</td>
<td align="left">ProjectionPoseYaw</td>
<td align="left">Described in align="left">RFC 9559, <xref target="projectionposeyaw-element"></xref></td> target="projectionposeyaw-element"/></td>
</tr>

<tr>
<td align="right">0x7674</td>
<td align="left">ProjectionPosePitch</td>
<td align="left">Described in align="left">RFC 9559, <xref target="projectionposepitch-element"></xref></td> target="projectionposepitch-element"/></td>
</tr>

<tr>
<td align="right">0x7675</td>
<td align="left">ProjectionPoseRoll</td>
<td align="left">Described in align="left">RFC 9559, <xref target="projectionposeroll-element"></xref></td> target="projectionposeroll-element"/></td>
</tr>

<tr>
<td align="right">0x78B5</td>
<td align="left">OutputSamplingFrequency</td>
<td align="left">Described in align="left">RFC 9559, <xref target="outputsamplingfrequency-element"></xref></td> target="outputsamplingfrequency-element"/></td>
</tr>

<tr>
<td align="right">0x7BA9</td>
<td align="left">Title</td>
<td align="left">Described in align="left">RFC 9559, <xref target="title-element"></xref></td> target="title-element"/></td>
</tr>

<tr>
<td align="right">0x7D7B</td>
<td align="left">ChannelPositions</td>
<td align="left">Reclaimed (<xref target="channelpositions-element"></xref>)</td> (RFC 9559, <xref target="channelpositions-element"/>)</td>
</tr>

<tr>
<td align="right">0x7FFF</td>
<td align="left">Reserved</td>
<td align="left">RFC 9559</td>
</tr>

<tr>
<td align="right">0x010000-0x203FFE</td>
<td align="left">Not valid for use as an Element ID</td>
<td align="left">RFC 9559, <xref target="matroska-element-ids-registry"/></td>
</tr>

<tr>
<td align="right">0x22B59C</td>
<td align="left">Language</td>
<td align="left">Described in align="left">RFC 9559, <xref target="language-element"></xref></td> target="language-element"/></td>
</tr>

<tr>
<td align="right">0x22B59D</td>
<td align="left">LanguageBCP47</td>
<td align="left">Described in align="left">RFC 9559, <xref target="languagebcp47-element"></xref></td> target="languagebcp47-element"/></td>
</tr>

<tr>
<td align="right">0x23314F</td>
<td align="left">TrackTimestampScale</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tracktimestampscale-element"></xref></td> target="tracktimestampscale-element"/></td>
</tr>

<tr>
<td align="right">0x234E7A</td>
<td align="left">DefaultDecodedFieldDuration</td>
<td align="left">Described in align="left">RFC 9559, <xref target="defaultdecodedfieldduration-element"></xref></td> target="defaultdecodedfieldduration-element"/></td>
</tr>

<tr>
<td align="right">0x2383E3</td>
<td align="left">FrameRate</td>
<td align="left">Reclaimed (<xref target="framerate-element"></xref>)</td> (RFC 9559, <xref target="framerate-element"/>)</td>
</tr>

<tr>
<td align="right">0x23E383</td>
<td align="left">DefaultDuration</td>
<td align="left">Described in align="left">RFC 9559, <xref target="defaultduration-element"></xref></td> target="defaultduration-element"/></td>
</tr>

<tr>
<td align="right">0x258688</td>
<td align="left">CodecName</td>
<td align="left">Described in align="left">RFC 9559, <xref target="codecname-element"></xref></td> target="codecname-element"/></td>
</tr>

<tr>
<td align="right">0x26B240</td>
<td align="left">CodecDownloadURL</td>
<td align="left">Reclaimed (<xref target="codecdownloadurl-element"></xref>)</td> (RFC 9559, <xref target="codecdownloadurl-element"/>)</td>
</tr>

<tr>
<td align="right">0x2AD7B1</td>
<td align="left">TimestampScale</td>
<td align="left">Described in align="left">RFC 9559, <xref target="timestampscale-element"></xref></td> target="timestampscale-element"/></td>
</tr>

<tr>
<td align="right">0x2EB524</td>
<td align="left">UncompressedFourCC</td>
<td align="left">Described in align="left">RFC 9559, <xref target="uncompressedfourcc-element"></xref></td> target="uncompressedfourcc-element"/></td>
</tr>

<tr>
<td align="right">0x2FB523</td>
<td align="left">GammaValue</td>
<td align="left">Reclaimed (<xref target="gammavalue-element"></xref>)</td> (RFC 9559, <xref target="gammavalue-element"/>)</td>
</tr>

<tr>
<td align="right">0x3A9697</td>
<td align="left">CodecSettings</td>
<td align="left">Reclaimed (<xref target="codecsettings-element"></xref>)</td> (RFC 9559, <xref target="codecsettings-element"/>)</td>
</tr>

<tr>
<td align="right">0x3B4040</td>
<td align="left">CodecInfoURL</td>
<td align="left">Reclaimed (<xref target="codecinfourl-element"></xref>)</td> (RFC 9559, <xref target="codecinfourl-element"/>)</td>
</tr>

<tr>
<td align="right">0x3C83AB</td>
<td align="left">PrevFilename</td>
<td align="left">Described in align="left">RFC 9559, <xref target="prevfilename-element"></xref></td> target="prevfilename-element"/></td>
</tr>

<tr>
<td align="right">0x3CB923</td>
<td align="left">PrevUUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="prevuuid-element"></xref></td> target="prevuuid-element"/></td>
</tr>

<tr>
<td align="right">0x3E83BB</td>
<td align="left">NextFilename</td>
<td align="left">Described in align="left">RFC 9559, <xref target="nextfilename-element"></xref></td> target="nextfilename-element"/></td>
</tr>

<tr>
<td align="right">0x3EB923</td>
<td align="left">NextUUID</td>
<td align="left">Described in align="left">RFC 9559, <xref target="nextuuid-element"/></td>
</tr>

<tr>
<td align="right">0x3FFFFF</td>
<td align="left">Reserved</td>
<td align="left">RFC 9559</td>
</tr>

<tr>
<td align="right">0x01000000-0x101FFFFE</td>
<td align="left">Not valid for use as an Element ID</td>
<td align="left">RFC 9559, <xref target="nextuuid-element"></xref></td> target="matroska-element-ids-registry"/></td>
</tr>

<tr>
<td align="right">0x1043A770</td>
<td align="left">Chapters</td>
<td align="left">Described in align="left">RFC 9559, <xref target="chapters-element"></xref></td> target="chapters-element"/></td>
</tr>

<tr>
<td align="right">0x114D9B74</td>
<td align="left">SeekHead</td>
<td align="left">Described in align="left">RFC 9559, <xref target="seekhead-element"></xref></td> target="seekhead-element"/></td>
</tr>

<tr>
<td align="right">0x1254C367</td>
<td align="left">Tags</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tags-element"></xref></td> target="tags-element"/></td>
</tr>

<tr>
<td align="right">0x1549A966</td>
<td align="left">Info</td>
<td align="left">Described in align="left">RFC 9559, <xref target="info-element"></xref></td> target="info-element"/></td>
</tr>

<tr>
<td align="right">0x1654AE6B</td>
<td align="left">Tracks</td>
<td align="left">Described in align="left">RFC 9559, <xref target="tracks-element"></xref></td> target="tracks-element"/></td>
</tr>

<tr>
<td align="right">0x18538067</td>
<td align="left">Segment</td>
<td align="left">Described in align="left">RFC 9559, <xref target="segment-element"></xref></td> target="segment-element"/></td>
</tr>

<tr>
<td align="right">0x1941A469</td>
<td align="left">Attachments</td>
<td align="left">Described in align="left">RFC 9559, <xref target="attachments-element"></xref></td> target="attachments-element"/></td>
</tr>

<tr>
<td align="right">0x1C53BB6B</td>
<td align="left">Cues</td>
<td align="left">Described in align="left">RFC 9559, <xref target="cues-element"></xref></td> target="cues-element"/></td>
</tr>

<tr>
<td align="right">0x1F43B675</td>
<td align="left">Cluster</td>
<td align="left">Described align="left">RFC 9559, <xref target="cluster-element"/></td>
</tr>

<tr>
<td align="right">0x1FFFFFFF</td>
<td align="left">Reserved</td>
<td align="left">RFC 9559</td>
</tr>

</tbody>
</table>
</section>

<section anchor="matroska-compression-algorithms-registry"><name>Matroska Compression Algorithms Registry</name>
<t>IANA has created a new registry called the "Matroska Compression Algorithms" registry.
The values correspond to the unsigned integer <tt>ContentCompAlgo</tt> value described in <xref target="contentcompalgo-element"/>.</t>
<t>To register a new Compression Algorithm in this registry, one needs a Compression Algorithm value,
a description, a Change Controller, and
a Reference to a document describing the Compression Algorithm.</t>
<t>The Compression Algorithms are to be allocated according to the "Specification Required" policy <xref target="RFC8126"/>. Available values range from 4-18446744073709551615.</t>
<t><xref target="compression-algorithm-registry-table"/> shows the initial contents of the "Matroska Compression Algorithms" registry.
The Change Controller for the initial entries is the IETF.</t>
<table anchor="compression-algorithm-registry-table"><name>Initial Contents of "Matroska Compression Algorithms" Registry</name>
<thead>
<tr>
<th align="right">Compression Algorithm</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">zlib</td>
<td align="left">RFC 9559, <xref target="contentcompalgo-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">bzlib</td>
<td align="left">RFC 9559, <xref target="contentcompalgo-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">lzo1x</td>
<td align="left">RFC 9559, <xref target="contentcompalgo-element"/></td>
</tr>

<tr>
<td align="right">3</td>
<td align="left">Header Stripping</td>
<td align="left">RFC 9559, <xref target="contentcompalgo-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-encryption-algorithms-registry"><name>Matroska Encryption Algorithms Registry</name>
<t>IANA has created a new registry called the "Matroska Encryption Algorithms" registry.
The values correspond to the unsigned integer <tt>ContentEncAlgo</tt> value described in <xref target="contentencalgo-element"/>.</t>
<t>To register a new Encryption Algorithm in this registry, one needs an Encryption Algorithm value,
a description, a Change Controller, and
an optional Reference to a document describing the Encryption Algorithm.</t>
<t>The Encryption Algorithms are to be allocated according to the "First Come First Served" policy <xref target="RFC8126"/>. Available values range from 6-18446744073709551615.</t>
<t><xref target="encryption-algorithm-registry-table"/> shows the initial contents of the "Matroska Encryption Algorithms" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="encryption-algorithm-registry-table"><name>Initial Contents of "Matroska Encryption Algorithms" Registry</name>
<thead>
<tr>
<th align="right">Encryption Algorithm</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">Not encrypted</td>
<td align="left">RFC 9559, <xref target="contentencalgo-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">DES</td>
<td align="left">RFC 9559, <xref target="contentencalgo-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">3DES</td>
<td align="left">RFC 9559, <xref target="contentencalgo-element"/></td>
</tr>

<tr>
<td align="right">3</td>
<td align="left">Twofish</td>
<td align="left">RFC 9559, <xref target="contentencalgo-element"/></td>
</tr>

<tr>
<td align="right">4</td>
<td align="left">Blowfish</td>
<td align="left">RFC 9559, <xref target="contentencalgo-element"/></td>
</tr>

<tr>
<td align="right">5</td>
<td align="left">AES</td>
<td align="left">RFC 9559, <xref target="contentencalgo-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-aes-cipher-modes-registry"><name>Matroska AES Cipher Modes Registry</name>
<t>IANA has created a new registry called the "Matroska AES Cipher Modes" registry.
The values correspond to the unsigned integer <tt>AESSettingsCipherMode</tt> value described in <xref target="aessettingsciphermode-element"/>.</t>
<t>To register a new AES Cipher Mode in this registry, one needs an AES Cipher Mode value,
a description, a Change Controller, and
an optional Reference to a document describing the AES Cipher Mode.</t>
<t>The AES Cipher Modes are to be allocated according to the "First Come First Served" policy <xref target="RFC8126"/>. Available values range from 3-18446744073709551615.</t>
<t>The value 0 is not valid for use as an AES Cipher Mode.</t>
<t><xref target="aes-cipher-mode-registry-table"/> shows the initial contents of the "Matroska AES Cipher Modes" registry.
The Change Controller for the initial entries is the IETF.</t>
<table anchor="aes-cipher-mode-registry-table"><name>Initial Contents of "Matroska AES Cipher Modes" Registry</name>
<thead>
<tr>
<th align="right">AES Cipher Mode</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">Not valid for use as an AES Cipher Mode</td>
<td align="left">RFC 9559, <xref target="aessettingsciphermode-element"/></td>
</tr>
<tr>
<td align="right">1</td>
<td align="left">AES-CTR</td>
<td align="left">RFC 9559, <xref target="aessettingsciphermode-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">AES-CBC</td>
<td align="left">RFC 9559, <xref target="aessettingsciphermode-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-content-encoding-scopes-registry"><name>Matroska Content Encoding Scopes Registry</name>
<t>IANA has created a new registry called the "Matroska Content Encoding Scopes" registry.
The values correspond to the unsigned integer <tt>ContentEncodingScope</tt> value described in <xref target="contentencodingscope-element"/>.</t>
<t>To register a new Content Encoding Scope in this registry, one needs a Content Encoding Scope value,
a description, a Change Controller, and
a Reference to a document describing the Content Encoding Scope.</t>
<t>The Content Encoding Scopes are to be allocated according to the "Specification Required" policy <xref target="RFC8126"/>. Available values range from 0x8-0x8000000000000000.</t>
<t>The Content Encoding Scope is a bit-field value, so only power of 2 values can be registered.</t>
<t>The value 0 is not valid for use as a Content Encoding Scope.</t>
<t><xref target="content-encoding-scope-registry-table"/> shows the initial contents of the "Matroska Content Encoding Scopes" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="content-encoding-scope-registry-table"><name>Initial Contents of "Matroska Content Encoding Scopes" Registry</name>
<thead>
<tr>
<th align="right">Content Encoding Scope</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0x0</td>
<td align="left">Not valid for use as a Content Encoding Scope</td>
<td align="left">RFC 9559, <xref target="contentencodingscope-element"/></td>
</tr>

<tr>
<td align="right">0x1</td>
<td align="left">Block</td>
<td align="left">RFC 9559, <xref target="contentencodingscope-element"/></td>
</tr>

<tr>
<td align="right">0x2</td>
<td align="left">Private</td>
<td align="left">RFC 9559, <xref target="contentencodingscope-element"/></td>
</tr>

<tr>
<td align="right">0x4</td>
<td align="left">Next</td>
<td align="left">RFC 9559, <xref target="contentencodingscope-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-content-encoding-types-registry"><name>Matroska Content Encoding Types Registry</name>
<t>IANA has created a new registry called the "Matroska Content Encoding Types" registry.
The values correspond to the unsigned integer <tt>ContentEncodingType</tt> value described in <xref target="contentencodingtype-element"/>.</t>
<t>To register a new Content Encoding Type in this registry, one needs a Content Encoding Type value,
a description, a Change Controller, and
a Reference to a document describing the Content Encoding Type.</t>
<t>The Content Encoding Types are to be allocated according to the "Specification Required" policy <xref target="RFC8126"/>. Available values range from 2-18446744073709551615.</t>
<t><xref target="content-encoding-type-registry-table"/> shows the initial contents of the "Matroska Content Encoding Types" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="content-encoding-type-registry-table"><name>Initial Contents of "Matroska Content Encoding Types" Registry</name>
<thead>
<tr>
<th align="right">Content Encoding Type</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">Compression</td>
<td align="left">RFC 9559, <xref target="contentencodingtype-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">Encryption</td>
<td align="left">RFC 9559, <xref target="contentencodingtype-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-stereo-modes-registry"><name>Matroska Stereo Modes Registry</name>
<t>IANA has created a new registry called the "Matroska Stereo Modes" registry.
The values correspond to the unsigned integer <tt>StereoMode</tt> value described in <xref target="stereomode-element"/>.</t>
<t>To register a new Stereo Mode in this registry, one needs a Stereo Mode value,
a description, a Change Controller, and
a Reference to a document describing the Stereo Mode.</t>
<t>The Stereo Modes are to be allocated according to the "Specification Required" policy <xref target="RFC8126"/>. Available values range from 15-18446744073709551615.</t>
<t><xref target="stereo-mode-registry-table"/> shows the initial contents of the "Matroska Stereo Modes" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="stereo-mode-registry-table"><name>Initial Contents of "Matroska Stereo Modes" Registry</name>
<thead>
<tr>
<th align="right">Stereo Mode</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">mono</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">side by side (left eye first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">top - bottom (right eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">3</td>
<td align="left">top - bottom (left eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">4</td>
<td align="left">checkboard (right eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">5</td>
<td align="left">checkboard (left eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">6</td>
<td align="left">row interleaved (right eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">7</td>
<td align="left">row interleaved (left eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">8</td>
<td align="left">column interleaved (right eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">9</td>
<td align="left">column interleaved (left eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">10</td>
<td align="left">anaglyph (cyan/red)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">11</td>
<td align="left">side by side (right eye first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">12</td>
<td align="left">anaglyph (green/magenta)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">13</td>
<td align="left">both eyes laced in one Block (left eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>

<tr>
<td align="right">14</td>
<td align="left">both eyes laced in one Block (right eye is first)</td>
<td align="left">RFC 9559, <xref target="stereomode-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-alpha-modes-registry"><name>Matroska Alpha Modes Registry</name>
<t>IANA has created a new registry called the "Matroska Alpha Modes" registry.
The values correspond to the unsigned integer <tt>AlphaMode</tt> value described in <xref target="alphamode-element"/>.</t>
<t>To register a new Alpha Mode in this registry, one needs an Alpha Mode value,
a description, a Change Controller, and
an optional Reference to a document describing the Alpha Mode.</t>
<t>The Alpha Modes are to be allocated according to the "First Come First Served" policy <xref target="RFC8126"/>. Available values range from 2-18446744073709551615.</t>
<t><xref target="alpha-mode-registry-table"/> shows the initial contents of the "Matroska Alpha Modes" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="alpha-mode-registry-table"><name>Initial Contents of "Matroska Alpha Modes" Registry</name>
<thead>
<tr>
<th align="right">Alpha Mode</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">none</td>
<td align="left">RFC 9559, <xref target="alphamode-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">present</td>
<td align="left">RFC 9559, <xref target="alphamode-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-display-units-registry"><name>Matroska Display Units Registry</name>
<t>IANA has created a new registry called the "Matroska Display Units" registry.
The values correspond to the unsigned integer <tt>DisplayUnit</tt> value described in <xref target="displayunit-element"/>.</t>
<t>To register a new Display Unit in this registry, one needs a Display Unit value,
a description, a Change Controller, and
a Reference to a document describing the Display Unit.</t>
<t>The Display Units are to be allocated according to the "Specification Required" policy <xref target="RFC8126"/>. Available values range from 5-18446744073709551615.</t>
<t><xref target="display-unit-registry-table"/> shows the initial contents of the "Matroska Display Units" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="display-unit-registry-table"><name>Initial Contents of "Matroska Display Units" Registry</name>
<thead>
<tr>
<th align="right">Display Unit</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">pixels</td>
<td align="left">RFC 9559, <xref target="displayunit-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">centimeters</td>
<td align="left">RFC 9559, <xref target="displayunit-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">inches</td>
<td align="left">RFC 9559, <xref target="displayunit-element"/></td>
</tr>

<tr>
<td align="right">3</td>
<td align="left">display aspect ratio</td>
<td align="left">RFC 9559, <xref target="displayunit-element"/></td>
</tr>

<tr>
<td align="right">4</td>
<td align="left">unknown</td>
<td align="left">RFC 9559, <xref target="displayunit-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-horizontal-chroma-sitings-registry"><name>Matroska Horizontal Chroma Sitings Registry</name>
<t>IANA has created a new registry called the "Matroska Horizontal Chroma Sitings" registry.
The values correspond to the unsigned integer <tt>ChromaSitingHorz</tt> value described in <xref target="chromasitinghorz-element"/>.</t>
<t>To register a new Horizontal Chroma Siting in this registry, one needs a Horizontal Chroma Siting value,
a description, a Change Controller, and
an optional Reference to a document describing the Horizontal Chroma Siting.</t>
<t>The Horizontal Chroma Sitings are to be allocated according to the "First Come First Served" policy <xref target="RFC8126"/>. Available values range from 3-18446744073709551615.</t>
<t><xref target="horizontal-chroma-siting-registry-table"/> shows the initial contents of the "Matroska Horizontal Chroma Sitings" registry.
The Change Controller for the initial entries is the IETF.</t>
<table anchor="horizontal-chroma-siting-registry-table"><name>Initial Contents of "Matroska Horizontal Chroma Sitings" Registry</name>
<thead>
<tr>
<th align="right">Horizontal Chroma Siting</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">unspecified</td>
<td align="left">RFC 9559, <xref target="chromasitinghorz-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">left collocated</td>
<td align="left">RFC 9559, <xref target="chromasitinghorz-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">half</td>
<td align="left">RFC 9559, <xref target="chromasitinghorz-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-vertical-chroma-sitings-registry"><name>Matroska Vertical Chroma Sitings Registry</name>
<t>IANA has created a new registry called the "Matroska Vertical Chroma Sitings" registry.
The values correspond to the unsigned integer <tt>ChromaSitingVert</tt> value described in <xref target="chromasitingvert-element"/>.</t>
<t>To register a new Vertical Chroma Siting in this registry, one needs a Vertical Chroma Siting value,
a description, a Change Controller, and
an optional Reference to a document describing the Vertical Chroma Siting.</t>
<t>The Vertical Chroma Sitings are to be allocated according to the "First Come First Served" policy <xref target="RFC8126"/>. Available values range from 3-18446744073709551615.</t>
<t><xref target="vertical-chroma-siting-registry-table"/> shows the initial contents of the "Matroska Vertical Chroma Sitings" registry.
The Change Controller for the initial entries is the IETF.</t>
<table anchor="vertical-chroma-siting-registry-table"><name>Initial Contents of "Matroska Vertical Chroma Sitings" Registry</name>
<thead>
<tr>
<th align="right">Vertical Chroma Siting</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">unspecified</td>
<td align="left">RFC 9559, <xref target="chromasitingvert-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">top collocated</td>
<td align="left">RFC 9559, <xref target="chromasitingvert-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">half</td>
<td align="left">RFC 9559, <xref target="chromasitingvert-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-color-ranges-registry"><name>Matroska Color Ranges Registry</name>
<t>IANA has created a new registry called the "Matroska Color Ranges" registry.
The values correspond to the unsigned integer <tt>Range</tt> value described in <xref target="cluster-element"></xref></td> target="color-range-element"/>.</t>
<t>To register a new Color Range in this registry, one needs a Color Range value,
a description, a Change Controller, and
a Reference to a document describing the Color Range.</t>
<t>The Color Ranges are to be allocated according to the "Specification Required" policy <xref target="RFC8126"/>. Available values range from 4-18446744073709551615.</t>
<t><xref target="color-range-registry-table"/> shows the initial contents of the "Matroska Color Ranges" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="color-range-registry-table"><name>Initial Contents of "Matroska Color Ranges" Registry</name>
<thead>
<tr>
<th align="right">Color Range</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">unspecified</td>
<td align="left">RFC 9559, <xref target="color-range-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">broadcast range</td>
<td align="left">RFC 9559, <xref target="color-range-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">full range (no clipping)</td>
<td align="left">RFC 9559, <xref target="color-range-element"/></td>
</tr>

<tr>
<td align="right">3</td>
<td align="left">defined by MatrixCoefficients / TransferCharacteristics</td>
<td align="left">RFC 9559, <xref target="color-range-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-tags-target-types-registry"><name>Matroska Tags Target Types Registry</name>
<t>IANA has created a new registry called the "Matroska Tags Target Types" registry.
The values correspond to the unsigned integer <tt>TargetTypeValue</tt> value described in <xref target="targettypevalue-element"/>.</t>
<t>To register a new Tags Target Type in this registry, one needs a Tags Target Type value,
a description, a Change Controller, and
a Reference to a document describing the Tags Target Type.</t>
<t>The Tags Target Types are to be allocated according to the "Specification Required" policy <xref target="RFC8126"/>. Available values range from 1-9, 11-19, 21-29, 31-39, 41-49, 51-59, 61-69, and 71-18446744073709551615.</t>
<t>The value 0 is not valid for use as a Tags Target Type.</t>
<t><xref target="tags-target-type-registry-table"/> shows the initial contents of the "Matroska Tags Target Types" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="tags-target-type-registry-table"><name>Initial Contents of "Matroska Tags Target Types" Registry</name>

<thead>
<tr>
<th align="right">Tags Target Type</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">70</td>
<td align="left">COLLECTION</td>
<td align="left">RFC 9559, <xref target="targettypevalue-element"/></td>
</tr>

<tr>
<td align="right">60</td>
<td align="left">EDITION / ISSUE / VOLUME / OPUS / SEASON / SEQUEL</td>
<td align="left">RFC 9559, <xref target="targettypevalue-element"/></td>
</tr>

<tr>
<td align="right">50</td>
<td align="left">ALBUM / OPERA / CONCERT / MOVIE / EPISODE</td>
<td align="left">RFC 9559, <xref target="targettypevalue-element"/></td>
</tr>

<tr>
<td align="right">40</td>
<td align="left">PART / SESSION</td>
<td align="left">RFC 9559, <xref target="targettypevalue-element"/></td>
</tr>

<tr>
<td align="right">30</td>
<td align="left">TRACK / SONG / CHAPTER</td>
<td align="left">RFC 9559, <xref target="targettypevalue-element"/></td>
</tr>

<tr>
<td align="right">20</td>
<td align="left">SUBTRACK / MOVEMENT / SCENE</td>
<td align="left">RFC 9559, <xref target="targettypevalue-element"/></td>
</tr>

<tr>
<td align="right">10</td>
<td align="left">SHOT</td>
<td align="left">RFC 9559, <xref target="targettypevalue-element"/></td>
</tr>

<tr>
<td align="right">0</td>
<td align="left">Not valid for use as a Tags Target Type</td>
<td align="left">RFC 9559, <xref target="targettypevalue-element"/></td>
</tr>
</tbody>
</table></section>
</table>
</section>

<section anchor="chapter-codec-ids-registry"><name>Chapter anchor="matroska-chapter-codec-ids-registry"><name>Matroska Chapter Codec IDs Registry</name>
<t>This document creates
<t>IANA has created a new IANA registry called the &quot;Matroska "Matroska Chapter Codec IDs&quot; IDs" registry.
The values correspond to the unsigned integer <tt>ChapProcessCodecID</tt> value <tt>ChapProcessCodecID</tt>, <tt>ChapterTranslateCodec</tt>, and <tt>TrackTranslateCodec</tt> values described in <xref target="chapprocesscodecid-element"></xref>.</t> target="chapprocesscodecid-element"/>.</t>
<t>To register a new Chapter Codec ID in this registry, one needs a Chapter Codec ID, ID value,
a description, a Change Controller (IETF or email of registrant) Controller, and
an optional
a Reference to a document describing the Chapter Codec ID.</t>
<t>The Chapter Codec IDs are to be allocated according to the &quot;First "Specification Required" policy <xref target="RFC8126"/>. Available values range from 2-18446744073709551615.</t>
<t><xref target="chapter-codec-id-registry-table"/> shows the initial contents of the "Matroska Chapter Codec IDs" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="chapter-codec-id-registry-table"><name>Initial Contents of "Matroska Chapter Codec IDs" Registry</name>
<thead>
<tr>
<th align="right">Chapter Codec ID</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">Matroska Script</td>
<td align="left">RFC 9559, <xref target="chapprocesscodecid-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">DVD-menu</td>
<td align="left">RFC 9559, <xref target="chapprocesscodecid-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-projection-types-registry"><name>Matroska Projection Types Registry</name>
<t>IANA has created a new registry called the "Matroska Projection Types" registry.
The values correspond to the unsigned integer <tt>ProjectionType</tt> value described in <xref target="projectiontype-element"/>.</t>
<t>To register a new Projection Type in this registry, one needs a Projection Type value,
a description, a Change Controller, and
an optional Reference to a document describing the Projection Type.</t>
<t>The Projection Types are to be allocated according to the "First Come First Served&quot; Served" policy <xref target="RFC8126"/>. Available values range from 4-18446744073709551615.</t>
<t><xref target="projection-type-registry-table"/> shows the initial contents of the "Matroska Projection Types" registry. The Change Controller for the initial entries is the IETF.
</t>
<table anchor="projection-type-registry-table"><name>Initial Contents of "Matroska Projection Types" Registry</name>
<thead>
<tr>
<th align="right">Projection Type</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">rectangular</td>
<td align="left">RFC 9559, <xref target="projectiontype-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">equirectangular</td>
<td align="left">RFC 9559, <xref target="projectiontype-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">cubemap</td>
<td align="left">RFC 9559, <xref target="projectiontype-element"/></td>
</tr>

<tr>
<td align="right">3</td>
<td align="left">mesh</td>
<td align="left">RFC 9559, <xref target="projectiontype-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-track-types-registry"><name>Matroska Track Types Registry</name>
<t>IANA has created a new registry called the "Matroska Track Types" registry.
The values correspond to the unsigned integer <tt>TrackType</tt> value described in <xref target="tracktype-element"/>.</t>
<t>To register a new Track Type in this registry, one needs a Track Type value,
a description, a Change Controller, and
a Reference to a document describing the Track Type.</t>
<t>The Track Types are to be allocated according to the "Specification Required" policy <xref target="RFC8126"></xref>.</t>
<t><tt>ChapProcessCodecID</tt> target="RFC8126"/>. Available values range from 4-15, 19-31, and 34-18446744073709551615.</t>
<t>The value 0 is not valid for use as a Track Type.</t>
<t><xref target="track-type-registry-table"/> shows the initial contents of &quot;0&quot; the "Matroska Track Types" registry.
The Change Controller for the initial entries is the IETF.</t>
<table anchor="track-type-registry-table"><name>Initial Contents of "Matroska Track Types" Registry</name>
<thead>
<tr>
<th align="right">Track Type</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>

<tr>
<td align="right">0</td>
<td align="left">Not valid for use as a Track Type</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>
<tr>
<td align="right">1</td>
<td align="left">video</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">audio</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>

<tr>
<td align="right">3</td>
<td align="left">complex</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>

<tr>
<td align="right">16</td>
<td align="left">logo</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>

<tr>
<td align="right">17</td>
<td align="left">subtitle</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>

<tr>
<td align="right">18</td>
<td align="left">buttons</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>

<tr>
<td align="right">32</td>
<td align="left">control</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>

<tr>
<td align="right">33</td>
<td align="left">metadata</td>
<td align="left">RFC 9559, <xref target="tracktype-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="matroska-track-plane-types-registry"><name>Matroska Track Plane Types Registry</name>
<t>IANA has created a new registry called the "Matroska Track Plane Types" registry.
The values correspond to the unsigned integer <tt>TrackPlaneType</tt> value described in <xref target="trackplanetype-element"/>.</t>
<t>To register a new Track Plane Type in this registry, one needs a Track Plane Type value,
a description, a Change Controller, and &quot;1&quot;
an optional Reference to a document describing the Track Plane Type.</t>
<t>The Track Plane Types are RESERVED to be allocated according to the IETF "First Come First Served" policy <xref target="RFC8126"/>. Available values range from 3-18446744073709551615.</t>
<t><xref target="track-plane-type-registry-table"/> shows the initial contents of the "Matroska Track Plane Types" registry.
The Change Controller for future use.</t> the initial entries is the IETF.</t>
<table anchor="track-plane-type-registry-table"><name>Initial Contents of "Matroska Track Plane Types" Registry</name>
<thead>
<tr>
<th align="right">Track Plane Type</th>
<th align="left">Description</th>
<th align="left">Reference</th>
</tr>
</thead>

<tbody>
<tr>
<td align="right">0</td>
<td align="left">left eye</td>
<td align="left">RFC 9559, <xref target="trackplanetype-element"/></td>
</tr>

<tr>
<td align="right">1</td>
<td align="left">right eye</td>
<td align="left">RFC 9559, <xref target="trackplanetype-element"/></td>
</tr>

<tr>
<td align="right">2</td>
<td align="left">background</td>
<td align="left">RFC 9559, <xref target="trackplanetype-element"/></td>
</tr>
</tbody>
</table>
</section>

<section anchor="media-types"><name>Media Types</name>
<t>Matroska files and streams are found in three main forms: audio-video files, audio-only audio-video,
audio-only, and occasionally with (occasionally) stereoscopic video tracks.</t>
<t>Historically video.</t>
<t>Historically, Matroska files and streams have used the following media types with a &quot;x-&quot; an "x-" prefix.
For better compatibility compatibility, a system <bcp14>SHOULD</bcp14> be able to handle both formats.
Newer systems <bcp14>SHOULD NOT</bcp14> use the historic format and use the format that follows the <xref target="RFC6838"></xref> format in <xref target="RFC6838"/> instead.</t>
<t>Please register
<t>IANA has registered three media types, types per the <xref target="RFC6838"></xref> templates are below:</t> (see <xref target="RFC6838"/>) in the following subsections.</t>

<section anchor="for-files-containing-video-tracks"><name>For files containing video tracks</name>

<dl spacing="compact"> Files Containing Video Tracks</name>

<dl>
<dt>Type name:</dt>
<dd>video</dd>
<dt>Subtype name:</dt>
<dd>matroska</dd>
<dt>Required parameters:</dt>
<dd>N/A</dd>
<dt>Optional parameters:</dt>
<dd>N/A</dd>
<dt>Encoding considerations:</dt>
<dd>as
<dd>As per this document RFCs 9559 and RFC8794</dd> 8794</dd>
<dt>Security considerations:</dt>
<dd>See <xref target="security-considerations"></xref>.</dd> target="security-considerations"/> of RFC 9559.</dd>
<dt>Interoperability considerations:</dt>
<dd>Due to the extensibility of Matroska, it is possible to encounter files with unknown but valid EBML Elements. Readers should be ready to handle this case. The fixed byte order, octet boundaries boundaries, and UTF-8 usage allow for broad interoparability.</dd> interoperability.</dd>
<dt>Published specification:</dt>
<dd>THISRFC</dd>
<dd>RFC 9559</dd>
<dt>Applications that use this media type:</dt>
<dd>FFmpeg, VLC, ...</dd> etc.</dd>
<dt>Fragment identifier considerations:</dt>
<dd>N/A</dd>
</dl>
<t>Additional information:</t>

<ul>
<li><t>Deprecated
<dd><t>N/A</t></dd>
<dt>Additional information:</dt>
<dd><t><br/></t>
<dl spacing="compact">
<dt>Deprecated alias names for this type: video/x-matroska</t>
</li>
<li><t>Magic number(s): N/A</t>
</li>
<li><t>File extension(s): mkv</t>
</li>
<li><t>Macintosh type:</dt>
<dd>video/x-matroska</dd>
<dt>Magic number(s):</dt>
<dd>N/A</dd>
<dt>File extension(s):</dt>
<dd>mkv</dd>
<dt>Macintosh file type code(s): N/A</t>
</li>
</ul>

<dl spacing="compact"> code(s):</dt>
<dd>N/A</dd></dl>
</dd>
<dt>Person &amp; email address to contact for further information:</dt>
<dd>IETF CELLAR WG cellar@ietf.org</dd> (cellar@ietf.org)</dd>
<dt>Intended usage:</dt>
<dd>COMMON</dd>
<dt>Restrictions on usage:</dt>
<dd>None</dd>
<dt>Author:</dt>
<dd>IETF CELLAR WG</dd>
<dt>Change controller:</dt>
<dd>IETF</dd>
<dt>Provisional registration? (standards tree only):</dt>
<dd>No</dd>
</dl>
</section>

<section anchor="for-files-containing-audio-tracks-with-no-video-tracks"><name>For files containing audio tracks Files Containing Audio Tracks with no video tracks</name>

<dl spacing="compact"> No Video Tracks</name>

<dl>
<dt>Type name:</dt>
<dd>audio</dd>
<dt>Subtype name:</dt>
<dd>matroska</dd>
<dt>Required parameters:</dt>
<dd>N/A</dd>
<dt>Optional parameters:</dt>
<dd>N/A</dd>
<dt>Encoding considerations:</dt>
<dd>as
<dd>As per this document RFCs 9559 and RFC8794</dd> 8794</dd>
<dt>Security considerations:</dt>
<dd>See <xref target="security-considerations"></xref>.</dd> target="security-considerations"/> of RFC 9559.</dd>
<dt>Interoperability considerations:</dt>
<dd>Due to the extensibility of Matroska, it is possible to encounter files with unknown but valid EBML Elements. Readers should be ready to handle this case. The fixed byte order, octet boundaries boundaries, and UTF-8 usage allow for broad interoparability.</dd> interoperability.</dd>
<dt>Published specification:</dt>
<dd>THISRFC</dd>
<dd>RFC 9559</dd>
<dt>Applications that use this media type:</dt>
<dd>FFmpeg, VLC, ...</dd> etc.</dd>
<dt>Fragment identifier considerations:</dt>
<dd>N/A</dd>
</dl>
<t>Additional information:</t>

<ul>
<li><t>Deprecated

<dt>Additional information:</dt>
<dd><t><br/></t>
<dl spacing="compact">

<dt>Deprecated alias names for this type: audio/x-matroska</t>
</li>
<li><t>Magic number(s): N/A</t>
</li>
<li><t>File extension(s): mka</t>
</li>
<li><t>Macintosh type:</dt>
<dd>audio/x-matroska</dd>
<dt>Magic number(s):</dt>
<dd>N/A</dd>
<dt>File extension(s):</dt>
<dd>mka</dd>
<dt>Macintosh file type code(s): N/A</t>
</li>
</ul>

<dl spacing="compact"> code(s):</dt>
<dd>N/A</dd>
</dl>
</dd>
<dt>Person &amp; email address to contact for further information:</dt>
<dd>IETF CELLAR WG cellar@ietf.org</dd> (cellar@ietf.org)</dd>
<dt>Intended usage:</dt>
<dd>COMMON</dd>
<dt>Restrictions on usage:</dt>
<dd>None</dd>
<dt>Author:</dt>
<dd>IETF CELLAR WG</dd>
<dt>Change controller:</dt>
<dd>IETF</dd>
<dt>Provisional registration? (standards tree only):</dt>
<dd>No</dd>
</dl>
</section>

<section anchor="for-files-containing-a-stereoscopic-video-track"><name>For files containing Files Containing a stereoscopic video track</name>

<dl spacing="compact"> Stereoscopic Video Track</name>

<dl>
<dt>Type name:</dt>
<dd>video</dd>
<dt>Subtype name:</dt>
<dd>matroska-3d</dd>
<dt>Required parameters:</dt>
<dd>N/A</dd>
<dt>Optional parameters:</dt>
<dd>N/A</dd>
<dt>Encoding considerations:</dt>
<dd>as
<dd>As per this document RFCs 9559 and RFC8794</dd> 8794</dd>
<dt>Security considerations:</dt>
<dd>See <xref target="security-considerations"></xref>.</dd> target="security-considerations"/> of RFC 9559.</dd>
<dt>Interoperability considerations:</dt>
<dd>Due to the extensibility of Matroska, it is possible to encounter files with unknown but valid EBML Elements. Readers should be ready to handle this case. The fixed byte order, octet boundaries boundaries, and UTF-8 usage allow for broad interoparability.</dd> interoperability.</dd>
<dt>Published specification:</dt>
<dd>THISRFC</dd>
<dd>RFC 9559</dd>
<dt>Applications that use this media type:</dt>
<dd>FFmpeg, VLC, ...</dd> etc.</dd>
<dt>Fragment identifier considerations:</dt>
<dd>N/A</dd>
</dl>
<t>Additional information:</t>

<ul>
<li><t>Deprecated

<dt>Additional information:</dt>
<dd><t><br/></t>
<dl spacing="compact">
<dt>Deprecated alias names for this type: video/x-matroska-3d</t>
</li>
<li><t>Magic number(s): N/A</t>
</li>
<li><t>File extension(s): mk3d</t>
</li>
<li><t>Macintosh type:</dt>
<dd>video/x-matroska-3d</dd>
<dt>Magic number(s):</dt>
<dd>N/A</dd>
<dt>File extension(s):</dt>
<dd>mk3d</dd>
<dt>Macintosh file type code(s): N/A</t>
</li>
</ul>

<dl spacing="compact"> code(s):</dt>
<dd>N/A</dd>
</dl>
</dd>
<dt>Person &amp; email address to contact for further information:</dt>
<dd>IETF CELLAR WG cellar@ietf.org</dd> (cellar@ietf.org)</dd>
<dt>Intended usage:</dt>
<dd>COMMON</dd>
<dt>Restrictions on usage:</dt>
<dd>None</dd>
<dt>Author:</dt>
<dd>IETF CELLAR WG</dd>
<dt>Change controller:</dt>
<dd>IETF</dd>
<dt>Provisional registration? (standards tree only):</dt>
<dd>No</dd>
</dl>
</section>
</section>
</section>

</middle>
<back>

<displayreference target="I-D.ietf-cellar-codec" to="MatroskaCodec"/>
<displayreference target="I-D.ietf-cellar-tags" to="MatroskaTags"/>
<references><name>References</name>

<references><name>Normative References</name>
<reference anchor="CIE-1931"  target="https://en.wikipedia.org/w/index.php?title=CIE_1931_color_space&amp;oldid=1242811504">
  <front>
    <title>CIE 1931 color space</title>
    <author>
      <organization>Wikipedia</organization>
    </author>
  </front>
</reference>

<reference anchor="ISO639-2" target="https://www.loc.gov/standards/iso639-2/php/code_list.php">
  <front>
    <title>Codes for the Representation of Names of Languages</title>
    <author>
      <organization>International Organization for Standardization</organization>
    </author>
    <date year="2017" month="December"></date>
  </front>
  <seriesInfo name="ISO" value="639-2"></seriesInfo>
</reference>

<reference anchor="ISO9899" target="https://www.iso.org/standard/74528.html">
  <front>
    <title>Information technology -- Programming languages -- C</title>
    <author>
      <organization>International Organization for Standardization</organization>
    </author>
    <date year="2018" month="June"></date>
  </front>
  <seriesInfo name="ISO/IEC" value="9899:2018"></seriesInfo>
</reference>

<reference anchor="ITU-H.273" target="https://www.itu.int/rec/T-REC-H.273-202309-P/en">
  <front>
    <title>Coding-independent code points for video signal type identification</title>
    <author>
      <organization>ITU-T</organization>
    </author>
    <date year="2023" month="September"></date>
  </front>
  <seriesInfo name="ITU-T Recommendation" value="H.273"></seriesInfo>
</reference>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.1950.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9562.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5646.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6838.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8081.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8126.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8794.xml"/>
</references>

<references><name>Informative References</name>

<reference anchor="AVIFormat" target="https://docs.microsoft.com/en-us/windows/win32/directshow/avi-riff-file-reference">
  <front>
    <title>AVI RIFF File Reference</title>
    <author>
      <organization>Microsoft Corporation</organization>
    </author>
    <date year="2023" month="June"></date>
  </front>
</reference>

<reference anchor="BZIP2" target="https://sourceware.org/bzip2/">
  <front>
    <title>bzip2</title>
    <author fullname="Julian Seward" initials="J." surname="Seward">
      <organization></organization>
    </author>
    <date year="2019" month="July"></date>
  </front>
</reference>

<reference anchor="Blowfish" target="https://www.schneier.com/academic/blowfish/">
  <front>
    <title>The Blowfish Encryption Algorithm</title>
    <author fullname="Bruce Schneier" initials="B." surname="Schneier">
      <organization></organization>
    </author>
    <date year="1993"></date>
  </front>
</reference>

<reference anchor="DVD-Video" target="http://www.dvdforum.org/">
  <front>
    <title>DVD-Books: Part 3 DVD-Video Book</title>
    <author>
      <organization>DVD Forum</organization>
    </author>
    <date year="1995" month="November"></date>
  </front>
</reference>

<reference anchor="DivXTrickTrack" target="https://web.archive.org/web/20101222001148/http://labs.divx.com/node/16601">
  <front>
    <title>Smooth FF/RW</title>
    <author></author>
    <date year="2010" month="December"></date>
  </front>
</reference>

<reference anchor="DivXWorldFonts" target="https://web.archive.org/web/20110214132246/http://labs.divx.com/node/16602">
  <front>
    <title>World Fonts</title>
    <author></author>
    <date year="2010" month="December"></date>
  </front>
</reference>

<reference anchor="Err7189" target="https://www.rfc-editor.org/errata/eid7189" quote-title="false">
  <front>
    <title>Erratum ID 7189</title>
    <author>
      <organization>RFC Errata</organization>
    </author>
  </front>
  <refcontent>RFC 8794</refcontent>
</reference>

<reference anchor="Err7191" target="https://www.rfc-editor.org/errata/eid7191" quote-title="false">
  <front>
    <title>Erratum ID 7191</title>
    <author>
      <organization>RFC Errata</organization>
    </author>
  </front>
  <refcontent>RFC 8794</refcontent>
</reference>

<reference anchor="FIPS197" target="https://csrc.nist.gov/publications/detail/fips/197/final">
  <front>
    <title>Advanced Encryption Standard (AES)</title>
    <author>
      <organization>National Institute of Standards and Technology (NIST)</organization>
    </author>
    <date year="2001" month="November"></date>
  </front>
  <seriesInfo name="FIPS" value="PUB 197"></seriesInfo>
  <seriesInfo name="DOI" value="10.6028/NIST.FIPS.197"></seriesInfo>
</reference>

<reference anchor="FIPS46-3" target="https://csrc.nist.gov/publications/detail/fips/46/3/archive/1999-10-25">
  <front>
    <title>Data Encryption Standard (DES)</title>
    <author>
      <organization>National Institute of Standards and Technology (NIST)</organization>
    </author>
    <date year="1999" month="October"></date>
  </front>
  <seriesInfo name="FIPS" value="PUB 46"></seriesInfo>
</reference>

<reference anchor="FourCC-RGB" target="https://web.archive.org/web/20160609214806/https://www.fourcc.org/rgb.php">
  <front>
    <title>RGB pixel formats</title>
    <author>
      <organization>FOURCC</organization>
    </author>
  </front>
</reference>

<reference anchor="FourCC-YUV" target="https://web.archive.org/web/20160609214806/https://www.fourcc.org/yuv.php">
  <front>
    <title>YUV pixel formats</title>
    <author>
      <organization>FOURCC</organization>
    </author>
  </front>
</reference>

<xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-cellar-codec.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml3/reference.I-D.ietf-cellar-tags.xml"/>

<reference anchor="JPEG" target="https://www.w3.org/Graphics/JPEG/itu-t81.pdf">
  <front>
    <title>INFORMATION TECHNOLOGY - DIGITAL COMPRESSION AND CODING OF CONTINUOUS-TONE STILL IMAGES - REQUIREMENTS AND GUIDELINES</title>
    <author>
      <organization>ITU-T</organization>
    </author>
    <date year="1992" month="September"></date>
  </front>
  <seriesInfo name="ITU-T Recommendation" value="T.81"></seriesInfo>
</reference>

<reference anchor="LZO" target="https://www.kernel.org/doc/Documentation/lzo.txt">
  <front>
    <title>LZO stream format as understood by Linux&#39;s LZO decompressor</title>
    <author fullname="Willy Tarreau" initials="W." surname="Tarreau">
      <organization></organization>
    </author>
    <author fullname="Dave Rodgman" initials="R." surname="Rodgman">
      <organization></organization>
    </author>
    <date year="2018" month="October"></date>
  </front>
</reference>

<reference anchor="MCF" target="http://mukoli.free.fr/mcf/">
  <front>
    <title>MCF specification, introduction</title>
    <author></author>
  </front>
</reference>

<reference anchor="MSRGB" target="https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-wmf/4e588f70-bd92-4a6f-b77f-35d0feaf7a57">
  <front>
    <title>Compression Enumeration</title>
    <author>
      <organization>Microsoft Corporation</organization>
    </author>
    <date year="2021" month="June"></date>
  </front>
</reference>

<reference anchor="MSYUV16" target="https://learn.microsoft.com/en-us/windows/win32/medfound/10-bit-and-16-bit-yuv-video-formats">
  <front>
    <title>10-bit and 16-bit YUV Video Formats</title>
    <author>
      <organization>Microsoft Corporation</organization>
    </author>
    <date year="2022" month="November"></date>
  </front>
</reference>

<reference anchor="MSYUV8" target="https://learn.microsoft.com/en-us/windows/win32/medfound/recommended-8-bit-yuv-formats-for-video-rendering">
  <front>
    <title>Recommended 8-Bit YUV Formats for Video Rendering</title>
    <author>
      <organization>Microsoft Corporation</organization>
    </author>
    <date year="2021" month="January"></date>
  </front>
</reference>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.0959.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2083.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3533.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4732.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9110.xml"/>

<reference anchor="SMB-CIFS" target="https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-CIFS/%5bMS-CIFS%5d.pdf">
  <front>
    <title>[MS-CIFS]: Common Internet File System (CIFS) Protocol</title>
    <author>
      <organization>Microsoft Corporation</organization>
    </author>
    <date year="2020" month="October"></date>
  </front>
</reference>

<reference anchor="SP800-38A" target="https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38a.pdf">
  <front>
    <title>Recommendation for Block Cipher Modes of Operation: Methods and Techniques</title>
    <author>
      <organization>National Institute of Standards and Technology (NIST)</organization>
    </author>
    <date year="2001" month="December"></date>
  </front>
  <seriesInfo name="DOI" value="10.6028/NIST.SP.800-38A"></seriesInfo>
  <seriesInfo name="NIST Special Publication" value="800-38A"></seriesInfo>
</reference>

<reference anchor="SP800-67" target="https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-67r2.pdf">
  <front>
    <title>Recommendation for the Triple Data Encryption Algorithm (TDEA) Block Cipher</title>
    <author>
      <organization>National Institute of Standards and Technology (NIST)</organization>
    </author>
    <date year="2017" month="November"></date>
  </front>
  <seriesInfo name="DOI" value="10.6028/NIST.SP.800-67r2"></seriesInfo>
  <seriesInfo name="NIST Special Publication" value="800-67"></seriesInfo>
</reference>

<reference anchor="Twofish" target="https://www.schneier.com/academic/archives/1998/06/twofish_a_128-bit_bl.html">
  <front>
    <title>Twofish: A 128-Bit Block Cipher</title>
    <author fullname="Bruce Schneier" initials="B." surname="Schneier">
      <organization></organization>
    </author>
    <author fullname="John Kelsey" initials="J." surname="Kelsey">
      <organization></organization>
    </author>
    <author fullname="Doug Whiting" initials="D." surname="Whiting">
      <organization></organization>
    </author>
    <author fullname="David Wagner" initials="D." surname="Wagner">
      <organization></organization>
    </author>
    <author fullname="Chris Hall" initials="C." surname="Hall">
      <organization></organization>
    </author>
    <author fullname="Niels Ferguson" initials="N." surname="Ferguson">
      <organization></organization>
    </author>
    <date year="1998" month="June"></date>
  </front>
</reference>

<reference anchor="WebM-Enc" target="https://www.webmproject.org/docs/webm-encryption/">
  <front>
    <title>WebM Encryption</title>
    <author fullname="Frank Galligan">
      <organization>Google</organization>
    </author>
    <date year="2016" month="September"></date>
  </front>
</reference>

<reference anchor="WebVTT" target="https://www.w3.org/TR/2019/CR-webvtt1-20190404/">
  <front>
    <title>WebVTT: The Web Video Text Tracks Format</title>
    <author fullname="Simon Pieters">
      <organization>Opera Software AS</organization>
    </author>
    <author fullname="Silvia Pfeiffer" role="editor">
      <organization>NICTA</organization>
    </author>
    <author fullname="Philip Jaegenstedt">
      <organization>Opera Software ASA</organization>
    </author>
    <author fullname="Ian Hickson">
      <organization>Google</organization>
    </author>
    <date year="2019" month="April"></date>
  </front>
  <refcontent>W3C Candidate Recommendation</refcontent>
</reference>

<reference anchor="libmatroska" target="https://github.com/Matroska-Org/libmatroska">
  <front>
    <title>libmatroska</title>
    <author></author>
    <date year="2024" month="March"></date>
  </front>
</reference>
</references>
</references>

<section anchor="annex-a-historic-deprecated-elements"><name>Annex A: Historic anchor="appendix-a-historic-deprecated-elements"><name>Historic Deprecated Elements</name>
<t>As Matroska has evolved since 2002 2002, many parts that were considered for use in the format were never
used and often incorrectly designed. Many of the elements that were then defined then are not
found in any known files but were part of public specs. DivX also had a few custom elements that
were designed for custom features.</t>
<t>We
<t>In this appendix, we list these elements that have a known ID that <bcp14>SHOULD NOT</bcp14> be reused to avoid colliding
with existing files. They These might be reassigned by IANA in the future if there are no more IDs for a given size.
A short description of what each ID was used for is included, but the text is not normative.</t>

<section anchor="silenttracks-element"><name>SilentTracks Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>master / 0x5854</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\SilentTracks</tt></dd>
<dt>documentation:</dt>
<dd>The list of tracks that are not used in that part of the stream.
It is useful when using overlay tracks on for seeking or to decide deciding what track to use.</dd>
</dl>
</section>

<section anchor="silenttracknumber-element"><name>SilentTrackNumber Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x58D7</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\SilentTracks\SilentTrackNumber</tt></dd>
<dt>documentation:</dt>
<dd>One of the track number numbers that are is not used from now on in the stream.
It could change later if not specified as silent in a further Cluster.</dd> <tt>Cluster</tt>.</dd>
</dl>
</section>

<section anchor="blockvirtual-element"><name>BlockVirtual Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>binary / 0xA2</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\BlockVirtual</tt></dd>
<dt>documentation:</dt>
<dd>A Block <tt>Block</tt> with no data. It must be stored in the stream at the place the real Block <tt>Block</tt> would be in display order.</dd>
</dl>
</section>

<section anchor="referencevirtual-element"><name>ReferenceVirtual Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>integer / 0xFD</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\ReferenceVirtual</tt></dd>
<dt>documentation:</dt>
<dd>The Segment Position <tt>Segment Position</tt> of the data that would otherwise be in position of the virtual block.</dd>
</dl>
</section>

<section anchor="slices-element"><name>Slices Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>master / 0x8E</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\Slices</tt></dd>
<dt>documentation:</dt>
<dd>Contains slices description.</dd>
</dl>
</section>

<section anchor="timeslice-element"><name>TimeSlice Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>master / 0xE8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\Slices\TimeSlice</tt></dd>
<dt>documentation:</dt>
<dd>Contains extra time information about the data contained in the Block. <tt>Block</tt>.
Being able to interpret this Element element is not required for playback.</dd>
</dl>
</section>

<section anchor="lacenumber-element"><name>LaceNumber Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xCC</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\Slices\TimeSlice\LaceNumber</tt></dd>
<dt>documentation:</dt>
<dd>The reverse number of the frame in the lace (0 is the last frame, 1 is the next to last, etc.).
Being able to interpret this Element element is not required for playback.</dd>

</dl>
</section>

<section anchor="framenumber-element"><name>FrameNumber Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xCD</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\Slices\TimeSlice\FrameNumber</tt></dd>
<dt>documentation:</dt>
<dd>The number of the frame to generate from this lace with this delay
(allow you to generate
(allows for the generation of many frames from the same Block/Frame).</dd>
</dl>
</section>

<section anchor="blockadditionid-element"><name>BlockAdditionID Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xCB</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\Slices\TimeSlice\BlockAdditionID</tt></dd>
<dt>documentation:</dt>
<dd>The ID of the BlockAdditional Element <tt>BlockAdditional</tt> element (0 is the main Block).</dd> <tt>Block</tt>).</dd>

</dl>
</section>

<section anchor="delay-element"><name>Delay Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xCE</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\Slices\TimeSlice\Delay</tt></dd>
<dt>documentation:</dt>
<dd>The delay to apply to the Element, element, expressed in Track Ticks; see <xref target="timestamp-ticks"></xref>.</dd> target="timestamp-ticks"/>.</dd>
</dl>
</section>

<section anchor="sliceduration-element"><name>SliceDuration Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xCF</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\Slices\TimeSlice\SliceDuration</tt></dd>
<dt>documentation:</dt>
<dd>The duration to apply to the Element, element, expressed in Track Ticks; see <xref target="timestamp-ticks"></xref>.</dd> target="timestamp-ticks"/>.</dd>
</dl>
</section>

<section anchor="referenceframe-element"><name>ReferenceFrame Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>master / 0xC8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\ReferenceFrame</tt></dd>
<dt>documentation:</dt>
<dd>Contains information about the last reference frame. See <xref target="DivXTrickTrack"></xref>.</dd> target="DivXTrickTrack"/>.</dd>
</dl>
</section>

<section anchor="referenceoffset-element"><name>ReferenceOffset Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xC9</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceOffset</tt></dd>
<dt>documentation:</dt>
<dd>The relative offset, in bytes, from the previous BlockGroup <tt>BlockGroup</tt> element for this Smooth FF/RW video track to the containing BlockGroup <tt>BlockGroup</tt>
element. See <xref target="DivXTrickTrack"></xref>.</dd> target="DivXTrickTrack"/>.</dd>
</dl>
</section>

<section anchor="referencetimestamp-element"><name>ReferenceTimestamp Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xCA</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceTimestamp</tt></dd>
<dt>documentation:</dt>
<dd>The timestamp of the BlockGroup <tt>BlockGroup</tt> pointed to by ReferenceOffset, expressed in Track Ticks; see <xref target="timestamp-ticks"></xref>. target="timestamp-ticks"/>. See <xref target="DivXTrickTrack"></xref>.</dd> target="DivXTrickTrack"/>.</dd>
</dl>
</section>

<section anchor="encryptedblock-element"><name>EncryptedBlock Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>binary / 0xAF</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cluster\EncryptedBlock</tt></dd>
<dt>documentation:</dt>
<dd>Similar to SimpleBlock, see <tt>SimpleBlock</tt> (see <xref target="simpleblock-structure"></xref>, target="simpleblock-structure"/>),
but the data inside the Block <tt>Block</tt> are Transformed (encrypt (encrypted and/or signed).</dd>
</dl>
</section>

<section anchor="mincache-element"><name>MinCache Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x6DE7</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\MinCache</tt></dd>
<dt>documentation:</dt>
<dd>The minimum number of frames a player should be able to cache during playback.
If set to 0, the reference pseudo-cache system is not used.</dd>
</dl>
</section>

<section anchor="maxcache-element"><name>MaxCache Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x6DF8</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\MaxCache</tt></dd>
<dt>documentation:</dt>
<dd>The maximum cache size necessary to store referenced frames in and the current frame.
0 means no cache is needed.</dd>
</dl>
</section>

<section anchor="trackoffset-element"><name>TrackOffset Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>integer / 0x537F</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOffset</tt></dd>
<dt>documentation:</dt>
<dd>A value to add to the Block's <tt>Block</tt>'s Timestamp, expressed in Matroska Ticks -- i.e., in nanoseconds; see <xref target="timestamp-ticks"></xref>. target="timestamp-ticks"/>.
This can be used to adjust the playback offset of a track.</dd>
</dl>
</section>

<section anchor="codecsettings-element"><name>CodecSettings Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>utf-8 / 0x3A9697</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\CodecSettings</tt></dd>
<dt>documentation:</dt>
<dd>A string describing the encoding setting used.</dd>
</dl>
</section>

<section anchor="codecinfourl-element"><name>CodecInfoURL Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>string / 0x3B4040</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\CodecInfoURL</tt></dd>
<dt>documentation:</dt>
<dd>A URL to find information about the codec used.</dd>
</dl>
</section>

<section anchor="codecdownloadurl-element"><name>CodecDownloadURL Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>string / 0x26B240</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\CodecDownloadURL</tt></dd>
<dt>documentation:</dt>
<dd>A URL to download information about the codec used.</dd>
</dl>
</section>

<section anchor="codecdecodeall-element"><name>CodecDecodeAll Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xAA</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\CodecDecodeAll</tt></dd>
<dt>documentation:</dt>
<dd>Set to 1 if the codec can decode potentially damaged data.</dd>
</dl>
</section>

<section anchor="trackoverlay-element"><name>TrackOverlay Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x6FAB</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrackOverlay</tt></dd>
<dt>documentation:</dt>
<dd>Specify that this track is an overlay track for the Track <tt>Track</tt> specified (in the u-integer).
That
This means that when this track has a gap on SilentTracks, <tt>SilentTracks</tt>, the overlay track should be used instead. The order of multiple TrackOverlay matters, <tt>TrackOverlay</tt> matters; the first one is the one that should be used.
If the first one is not found found, it should be the second, etc.</dd>
</dl>
</section>

<section anchor="aspectratiotype-element"><name>AspectRatioType Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x54B3</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\AspectRatioType</tt></dd>
<dt>documentation:</dt>
<dd>Specify
<dd>Specifies the possible modifications to the aspect ratio.</dd>
</dl>
</section>

<section anchor="gammavalue-element"><name>GammaValue Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>float / 0x2FB523</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\GammaValue</tt></dd>
<dt>documentation:</dt>
<dd>Gamma Value.</dd> value.</dd>
</dl>
</section>

<section anchor="framerate-element"><name>FrameRate Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>float / 0x2383E3</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Video\FrameRate</tt></dd>
<dt>documentation:</dt>
<dd>Number of frames per second. This value is Informational informational only. It is intended for constant frame rate streams, streams and should not be
used for a variable frame rate TrackEntry.</dd> <tt>TrackEntry</tt>.</dd>
</dl>
</section>

<section anchor="channelpositions-element"><name>ChannelPositions Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>binary / 0x7D7B</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\Audio\ChannelPositions</tt></dd>
<dt>documentation:</dt>
<dd>Table of horizontal angles for each successive channel.</dd>
</dl>
</section>

<section anchor="tricktrackuid-element"><name>TrickTrackUID Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xC0</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrickTrackUID</tt></dd>
<dt>documentation:</dt>
<dd>The TrackUID <tt>TrackUID</tt> of the Smooth FF/RW video in the paired EBML structure corresponding to this video track. See <xref target="DivXTrickTrack"></xref>.</dd> target="DivXTrickTrack"/>.</dd>
</dl>
</section>

<section anchor="tricktracksegmentuid-element"><name>TrickTrackSegmentUID Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>binary / 0xC1</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrickTrackSegmentUID</tt></dd>
<dt>documentation:</dt>
<dd>The SegmentUID <tt>SegmentUUID</tt> of the Segment <tt>Segment</tt> containing the track identified by TrickTrackUID. See <xref target="DivXTrickTrack"></xref>.</dd> target="DivXTrickTrack"/>.</dd>
</dl>
</section>

<section anchor="tricktrackflag-element"><name>TrickTrackFlag Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xC6</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrickTrackFlag</tt></dd>
<dt>documentation:</dt>
<dd>Set to 1 if this video track is a Smooth FF/RW track. If set to 1, MasterTrackUID <tt>MasterTrackUID</tt> and MasterTrackSegUID <tt>MasterTrackSegUID</tt> should be present present, and BlockGroups
<tt>BlockGroups</tt> for this track must contain ReferenceFrame structures.
Otherwise, TrickTrackUID and TrickTrackSegUID must be present if this track has a corresponding Smooth FF/RW track. See <xref target="DivXTrickTrack"></xref>.</dd> target="DivXTrickTrack"/>.</dd>
</dl>
</section>

<section anchor="trickmastertrackuid-element"><name>TrickMasterTrackUID Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xC7</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrickMasterTrackUID</tt></dd>
<dt>documentation:</dt>
<dd>The TrackUID <tt>TrackUID</tt> of the video track in the paired EBML structure that corresponds to this Smooth FF/RW track. See <xref target="DivXTrickTrack"></xref>.</dd> target="DivXTrickTrack"/>.</dd>
</dl>
</section>

<section anchor="trickmastertracksegmentuid-element"><name>TrickMasterTrackSegmentUID Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>binary / 0xC4</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\TrickMasterTrackSegmentUID</tt></dd>
<dt>documentation:</dt>
<dd>The SegmentUID <tt>SegmentUUID</tt> of the Segment <tt>Segment</tt> containing the track identified by MasterTrackUID. See <xref target="DivXTrickTrack"></xref>.</dd> target="DivXTrickTrack"/>.</dd>
</dl>
</section>

<section anchor="contentsignature-element"><name>ContentSignature Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>binary / 0x47E3</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption\ContentSignature</tt></dd>
<dt>documentation:</dt>
<dd>A cryptographic signature of the contents.</dd>
</dl>
</section>

<section anchor="contentsigkeyid-element"><name>ContentSigKeyID Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>binary / 0x47E4</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption\ContentSigKeyID</tt></dd>
<dt>documentation:</dt>
<dd>This is the ID of the private key that the data was signed with.</dd>
</dl>
</section>

<section anchor="contentsigalgo-element"><name>ContentSigAlgo Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x47E5</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption\ContentSigAlgo</tt></dd>
<dt>documentation:</dt>
<dd>The algorithm used for the signature.</dd>
</dl>
</section>

<section anchor="contentsighashalgo-element"><name>ContentSigHashAlgo Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x47E6</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\ContentEncryption\ContentSigHashAlgo</tt></dd>
<dt>documentation:</dt>
<dd>The hash algorithm used for the signature.</dd>
</dl>
</section>

<section anchor="cuerefcluster-element"><name>CueRefCluster Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x97</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefCluster</tt></dd>
<dt>documentation:</dt>
<dd>The Segment Position <tt>Segment Position</tt> of the Cluster <tt>Cluster</tt> containing the referenced Block.</dd> <tt>Block</tt>.</dd>
</dl>
</section>

<section anchor="cuerefnumber-element"><name>CueRefNumber Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x535F</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefNumber</tt></dd>
<dt>documentation:</dt>
<dd>Number of the referenced Block <tt>Block</tt> of Track X in the specified Cluster.</dd> <tt>Cluster</tt>.</dd>
</dl>
</section>

<section anchor="cuerefcodecstate-element"><name>CueRefCodecState Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0xEB</dd>
<dt>path:</dt>
<dd><tt>\Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefCodecState</tt></dd>
<dt>documentation:</dt>
<dd>The Segment Position <tt>Segment Position</tt> of the Codec State corresponding to this referenced Element. element.
0 means that the data is taken from the initial Track Entry.</dd> <tt>TrackEntry</tt>.</dd>
</dl>
</section>

<section anchor="filereferral-element"><name>FileReferral Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>binary / 0x4675</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile\FileReferral</tt></dd>
<dt>documentation:</dt>
<dd>A binary value that a track/codec can refer to when the attachment is needed.</dd>
</dl>
</section>

<section anchor="fileusedstarttime-element"><name>FileUsedStartTime Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x4661</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile\FileUsedStartTime</tt></dd>
<dt>documentation:</dt>
<dd>The timestamp at which this optimized font attachment comes into context, expressed in Segment Ticks Ticks, which is are based on TimestampScale.
<tt>TimestampScale</tt>. See <xref target="DivXWorldFonts"></xref>.</dd> target="DivXWorldFonts"/>.</dd>
</dl>
</section>

<section anchor="fileusedendtime-element"><name>FileUsedEndTime Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x4662</dd>
<dt>path:</dt>
<dd><tt>\Segment\Attachments\AttachedFile\FileUsedEndTime</tt></dd>
<dt>documentation:</dt>
<dd>The timestamp at which this optimized font attachment goes out of context, expressed in Segment Ticks Ticks, which is are based on TimestampScale.
<tt>TimestampScale</tt>. See <xref target="DivXWorldFonts"></xref>.</dd> target="DivXWorldFonts"/>.</dd>
</dl>
</section>

<section anchor="tagdefaultbogus-element"><name>TagDefaultBogus Element</name>

<dl spacing="compact">
<dt>type / id:</dt>
<dd>uinteger / 0x44B4</dd>
<dt>path:</dt>
<dd><tt>\Segment\Tags\Tag\+SimpleTag\TagDefaultBogus</tt></dd>
<dt>documentation:</dt>
<dd>A variant of the TagDefault <tt>TagDefault</tt> element with a bogus Element element ID; see <xref target="tagdefault-element"></xref>.</dd> target="tagdefault-element"/>.</dd>
</dl>
</section>
</section>

</middle>

<back>
<references><name>Normative References</name>
<reference anchor="BCP47" target="https://www.rfc-editor.org/info/rfc5646">
  <front>
    <title>Tags for Identifying Languages</title>
    <author fullname="A. Phillips" initials="A." surname="Phillips" role="editor">
      <organization></organization>
    </author>
    <author fullname="M. Davis" initials="M." surname="Davis" role="editor">
      <organization></organization>
    </author>
    <date year="2009" month="September"></date>
  </front>
  <seriesInfo name="BCP" value="47"></seriesInfo>
  <seriesInfo name="RFC" value="5646"></seriesInfo>
  <seriesInfo name="DOI" value="10.17487/RFC5646"></seriesInfo>
</reference>
<reference anchor="CIE-1931" target="https://en.wikipedia.org/wiki/CIE_1931_color_space">
  <front>
    <title>CIE 1931 Standard Colorimetric System</title>
    <author>
      <organization>Commission Internationale de l&#39;Eclairage</organization>
    </author>
    <date year="1931"></date>
  </front>
</reference>
<reference anchor="ISO639-2" target="https://www.loc.gov/standards/iso639-2/php/code_list.php">
  <front>
    <title>Codes for the Representation of Names of Languages</title>
    <author>
      <organization>United States Library Of Congress</organization>
    </author>
    <date year="2017" month="December" day="21"></date>
  </front>
  <seriesInfo name="ISO" value="639-2:1998"></seriesInfo>
</reference>
<reference anchor="ISO9899" target="https://www.iso.org/standard/57853.html">
  <front>
    <title>Information technology -- Programming languages -- C</title>
    <author>
      <organization>International Organization for Standardization</organization>
    </author>
    <date year="2011"></date>
  </front>
  <seriesInfo name="ISO/IEC" value="9899:2011"></seriesInfo>
</reference>
<reference anchor="ITU-H.273" target="https://www.itu.int/rec/T-REC-H.273/en">
  <front>
    <title>Coding-independent code points for video signal type identification</title>
    <author>
      <organization>International Telecommunication Union</organization>
    </author>
    <date year="2021" month="September" day="24"></date>
  </front>
  <seriesInfo name="ITU" value="H.273"></seriesInfo>
</reference>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.1950.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4122.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6838.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8081.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8126.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8794.xml"/>
</references>
<references><name>Informative References</name>
<reference anchor="AVIFormat" target="https://docs.microsoft.com/en-us/windows/win32/directshow/avi-riff-file-reference">
  <front>
    <title>AVI RIFF File Reference</title>
    <author>
      <organization>Microsoft</organization>
    </author>
    <date year="2018" month="May" day="31"></date>
  </front>
</reference>
<reference anchor="BZIP2" target="https://sourceware.org/bzip2/">
  <front>
    <title>bzip2</title>
    <author fullname="Julian Seward" initials="J." surname="Seward">
      <organization></organization>
    </author>
    <date year="1996" month="July" day="18"></date>
  </front>
</reference>
<reference anchor="Blowfish" target="https://www.schneier.com/academic/blowfish/">
  <front>
    <title>The Blowfish Encryption Algorithm</title>
    <author fullname="Bruce Schneier" initials="B." surname="Schneier">
      <organization></organization>
    </author>
    <date year="1993"></date>
  </front>
</reference>
<reference anchor="DVD-Video" target="http://www.dvdforum.org/">
  <front>
    <title>DVD-Books: Part 3 DVD-Video Book</title>
    <author>
      <organization>DVD Forum</organization>
    </author>
    <date year="1995" month="November" day="1"></date>
  </front>
</reference>
<reference anchor="DivXTrickTrack" target="https://web.archive.org/web/20101222001148/http://labs.divx.com/node/16601">
  <front>
    <title>DivX Trick Track Extensions</title>
    <author></author>
    <date year="2010" month="December" day="14"></date>
  </front>
</reference>
<reference anchor="DivXWorldFonts" target="https://web.archive.org/web/20110214132246/http://labs.divx.com/node/16602">
  <front>
    <title>DivX World Fonts Extensions</title>
    <author></author>
    <date year="2010" month="December" day="14"></date>
  </front>
</reference>
<reference anchor="FIPS.197" target="https://csrc.nist.gov/publications/detail/fips/197/final">
  <front>
    <title>Advanced Encryption Standard (AES)</title>
    <author>
      <organization>US National Institute of Standards and Technology</organization>
    </author>
    <date year="2001" month="November" day="26"></date>
  </front>
  <seriesInfo name="FIPS" value="PUB 197"></seriesInfo>
  <seriesInfo name="DOI" value="10.6028/NIST.FIPS.197"></seriesInfo>
</reference>
<reference anchor="FIPS.46-3" target="https://csrc.nist.gov/publications/detail/fips/46/3/archive/1999-10-25">
  <front>
    <title>Data Encryption Standard (DES)</title>
    <author>
      <organization>US National Institute of Standards and Technology</organization>
    </author>
    <date year="1999" month="October" day="25"></date>
  </front>
  <seriesInfo name="FIPS" value="PUB 46"></seriesInfo>
</reference>
<reference anchor="FourCC-RGB" target="https://web.archive.org/web/20160609214806/https://www.fourcc.org/rgb.php">
  <front>
    <title>RGB Pixel Format FourCCs</title>
    <author>
      <organization>Silicon.dk ApS</organization>
    </author>
  </front>
</reference>
<reference anchor="FourCC-YUV" target="https://web.archive.org/web/20160609214806/https://www.fourcc.org/yuv.php">
  <front>
    <title>YUV Pixel Format FourCCs</title>
    <author>
      <organization>Silicon.dk ApS</organization>
    </author>
  </front>
</reference>
<reference anchor="JPEG" target="https://www.w3.org/Graphics/JPEG/itu-t81.pdf">
  <front>
    <title>Digital Compression and Coding of Continuous-Tone Still Images</title>
    <author>
      <organization>International Telegraph and Telephone Consultative Committee</organization>
    </author>
    <date year="1992" month="September"></date>
  </front>
  <seriesInfo name="ITU" value="T.81"></seriesInfo>
</reference>
<reference anchor="LZO" target="https://www.kernel.org/doc/Documentation/lzo.txt">
  <front>
    <title>Lempel-Ziv-Oberhumer compression</title>
    <author fullname="Willy Tarreau" initials="W." surname="Tarreau">
      <organization></organization>
    </author>
    <author fullname="Dave Rodgman" initials="R." surname="Rodgman">
      <organization></organization>
    </author>
    <author fullname="Markus Oberhumer" initials="M." surname="Oberhumer">
      <organization></organization>
    </author>
    <date year="2018" month="October" day="30"></date>
  </front>
</reference>
<reference anchor="MCF" target="http://mukoli.free.fr/mcf/">
  <front>
    <title>Media Container Format</title>
    <author></author>
    <date year="2002" month="July" day="17"></date>
  </front>
</reference>
<reference anchor="MSRGB" target="https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-wmf/4e588f70-bd92-4a6f-b77f-35d0feaf7a57">
  <front>
    <title>WMF Compression Enumeration</title>
    <author>
      <organization>Microsoft</organization>
    </author>
  </front>
</reference>
<reference anchor="MSYUV16" target="https://learn.microsoft.com/en-us/windows/win32/medfound/10-bit-and-16-bit-yuv-video-formats">
  <front>
    <title>10-bit and 16-bit YUV Video Formats</title>
    <author>
      <organization>Microsoft</organization>
    </author>
  </front>
</reference>
<reference anchor="MSYUV8" target="https://learn.microsoft.com/en-us/windows/win32/medfound/recommended-8-bit-yuv-formats-for-video-rendering">
  <front>
    <title>Recommended 8-Bit YUV Formats for Video Rendering</title>
    <author>
      <organization>Microsoft</organization>
    </author>
  </front>
</reference>
<reference anchor="MatroskaCodec" target="">
  <front>
    <title>Media Container Codec Specifications</title>
    <author fullname="Steve Lhomme" initials="S." surname="Lhomme"></author>
    <author fullname="Moritz Bunkus" initials="M." surname="Bunkus"></author>
    <author fullname="Dave Rice" initials="D." surname="Rice"></author>
    <date year="2021" month="April" day="12"></date>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-ietf-cellar-codec-10"></seriesInfo>
</reference>
<reference anchor="MatroskaTags" target="">
  <front>
    <title>Matroska Media Container Tag Specifications</title>
    <author fullname="Steve Lhomme" initials="S." surname="Lhomme"></author>
    <author fullname="Moritz Bunkus" initials="M." surname="Bunkus"></author>
    <author fullname="Dave Rice" initials="D." surname="Rice"></author>
    <date year="2021" month="April" day="12"></date>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-ietf-cellar-tags-10"></seriesInfo>
</reference>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.0959.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2083.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.3533.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.9110.xml"/>
<reference anchor="SMB-CIFS" target="https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-CIFS/%5bMS-CIFS%5d.pdf">
  <front>
    <title>Common Internet File System (CIFS) Protocol</title>
    <author>
      <organization>Microsoft Corporation</organization>
    </author>
    <date year="2020" month="October" day="1"></date>
  </front>
</reference>
<reference anchor="SP.800-38A" target="https://csrc.nist.gov/publications/detail/fips/197/final">
  <front>
    <title>Recommendation for Block Cipher Modes of Operation: Methods and Techniques</title>
    <author>
      <organization>US National Institute of Standards and Technology</organization>
    </author>
    <date year="2001" month="December" day="01"></date>
  </front>
  <seriesInfo name="DOI" value="10.6028/NIST.SP.800-38A"></seriesInfo>
</reference>
<reference anchor="SP.800-67" target="https://csrc.nist.gov/publications/detail/sp/800-67/rev-2/final">
  <front>
    <title>Recommendation for the Triple Data Encryption Algorithm (TDEA) Block Cipher</title>
    <author>
      <organization>US National Institute of Standards and Technology</organization>
    </author>
    <date year="2017" month="November" day="01"></date>
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</reference>
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</back>

</rfc>